Well, as of right now, PSIP data (Program and System Information Protocol) is not mandated by the FCC and is strictly voluntary by the broadcasters. If boxes exist that use PSIP data to skip the recording of commercials on PVR devices, broadcasters will simply not broadcast PSIP data. DirecTV is a seperate issue because they use a proprietary data scheme.
As far as VCRs with commercial killers:
1). Since it is analog medium they are at best guessing where the commercials are. And some stations do put measures into broadcasts to disrupt them. Usually during special events. Things like skipping or doubling the little pause between content and commercials.
2). VCRs are lossy storage devices. Making copies of copies of copies degrades the quality of the program. With digital devices, an nth generation copy has the same quality as the 1st generation. So VCRs have a lot more leeway with broadcasters since what they are limited to is considered fair use. With digital devices, the very real possibility exists that a program can be recorded, stripped of commercials and rebroadcast or posted on the internet, which is piracy of content.
3). The Digital Millenium Copyright Act states “…the DMCA prohibits the manufacture and distribution of the means of circumventing technological measures protecting the rights of a copyright owner…” which was written to apply to conditional access programs, but could be applied to modification of copyrighted content. I’m still digging into this one.