It seems like dry-erase boards are becoming more common than chalkboards. And in the near future, no doubt, some type of digital system will surpass the dry erase board. Chalk is also dusty; it leaves residue on hands, which nobody likes; people are allergic to the dust. And as far as I know, it is a limited natural resource which must be extracted from the environment.
When will stores stop selling chalk altogether?
Someday, maybe, but probably not anytime soon.
As for digital systems, they already exist, but the current ones require a projector and probably a decent amount of upfront cash. I’d imagine long before the projector ones take over an LCD or plasma version will be available. The only nice thing about a projector version is that you can roll up the screen and get it out of the way.
Not anytime soon, with people out there painting every available surface with chalkboard paint.
Go check out the sidewalks at any college campus and it’s pretty clear chalk is still in use.
Chalk has advantages even over dry-erase markers (and digital media). It’s cheap, so you can have pieces of it everywhere, and no one is likely to walk away with it. You don’t have to recap it (and it never dries out). You don’t need to “clean” a chalk board nearly as often as a white board.
These advantages outweigh the dust-factor for most situations–there will always be contexts where it isn’t obsolete, just as with pencils.
dry erase boards are damaged when things that are not dry erase markers are used.
As far as i know chalk (very expensive chalk) is used by scrapbookers
Not as long as Glenn Beck is around. 
I’ve never seen a chalkboard in a classroom that wasn’t in a movie (born 1985). Sidewalk chalk is another matter, though.
There is also the “smart board” that the college i went to used. Its a digital version of a dry erase board.
You can’t make a hopscotch pattern on a dry erase board. And I used to give my daughter a bucket of colored chalk and tell her to go have fun on the driveway and porch. I couldn’t have afforded a dry erase board that big.
However, I do like my dry erase board on the fridge, it’s very handy.
Smart boards suck, though. We had them in every room at my high school but they were never used. Takes a good 5 minutes to calibrate the board anyway, and as with any computer program its buggy (buggier than physically writing on a board). I see dry-erase boards being the standard for a good while.
Not likely!
The school systems here in Minnesota have been so starved of funds that they haven’t even painted* rooms for at least 8 years! It will be decades before they replace the thousands of chalkboards with dry-erase boards, much less some digital electronic board.
*Yes, literally, painting the walls. We have held Precinct Caucus meetings in the local high school for the past 8 years, using most of the same rooms. Some of them needed painting 8 years ago, and need it worse now. But no painting has been done.
Blackboard chalk is actually gypsum - so we’d be up against a shortage of drywall board long before we’ve exhausted the planet’s mineral capacity to provide writing chalks.
Where are you? I was a school photographer from 2001-2009 on Long Island (NY); chalkboards in every school. (Elem., Middle and High.) Very few dry-erase boards, and I only saw an electronic one twice.
ETA: Just checked your profile. What part of LA?
Old technology takes a long time to die, especially when heavily embedded in conservative, institutions with limited funding. On a new installation, are dry erase boards cheaper?
There was a plumbing thread recently where I pointed out that the inferior gate valves have been obsolete for over 40 years, but the stores are still full of them.
Technology seems different. I was amazed how quickly VCR replaced Betamax. Now somebody wondered how long rewind will last.
I was so sad when all the remodeling at my undergrad alma mater got rid of the chalkboards - they were the real old slate kind. 
Know how to keep 3 young girls busy for an afternoon? Draw a 20 ft high elephant on the driveway, and let them color it in.
As someone who teaches math at a university, I see chalk boards all the time with only the occasional marker board. Personally, I prefer chalk to makers. For one thing, it’s a lot easier to clean chalk off your hands than it is to clean marker ink off your hands. And there are the reasons guizot gave as well. I also find that it is easier to draw or write more precisely with chalk than with markers, but that may just be me.
All of our classrooms also have “smart boards”. I hate them. Well, I wouldn’t mind them so much if they weren’t completely immobile. At least with projector screens, you can roll up the screens when you’re done, but the smart boards stay put, and they usually cover up the middle third of the chalk boards, leaving much less room for someone (like myself) who needs to use a lot of the chalk board.
I have occasionally used the smart boards, but for me personally, they’re a pain in the ***. First, you have to turn on the computer connected to it and wait for it to be ready. Then, you’ve got to get the remote controls and hope they’re working. And then, once everything’s perfectly ready… assuming you don’t need to recalibrate the settings… you have something that works just as well as an ordinary board. Yay! Keep the class waiting for 5 or 10 minutes just to have an ordinary board!
Now, I know that smart boards do have uses. They can show anything a computer can show, so they’re great for showing Powerpoint slides, for example. And then you can draw on your slides. That’s great for people who like to lecture with slides. Generally, though, I find writing material on the board myself helps keep the class flowing at a reasonable rate (whereas I might be tempted to zoom through the slides). And since I don’t have any ridiculously complicated pictures to show that I can’t easily draw (unlike, say, the biology professors), I have no real need for the smart boards. They just get in the way. If they were a bit more optional, if they could be moved out of the way, they’d be a lot better, imho.
One distinct advantage of a dry-erase (white) board in the classroom is that you can also use it as an OHP (or LCD) screen. Then you (or the students) can write “on” the OHP image with markers. What you (or they) write can be easily and quickly erased and re-written without altering the imagine coming from the projector. It’s like having a huge, re-usable worksheet that the whole room can see.
However, in rooms where I have the authority, I ask for a Lightning Board to be installed. This serves as both a chalk board, dry-erase board, and OHP-LCD screen. You can even write on it with pencil and pen. Everything washes off of it easily with a damp paper towel–no need for that expensive, scam erasure fluid.
It’s also metal, so that magnets can be used to fasten paper visuals to the board.