The point is, Disney’s intellectual property is protected by both copyright and trademark law, which cover different things in different ways and have very little overlap. And while some copyrights will soon be ending, Disney can hold onto their trademarks for as long as they want to.
Right now, if I take a copy of Steamboat Willie or Fantasia and burn it to a DVD, or post it on YouTube, I can get in trouble for violating copyright. If I draw my own picture of Mickey on a shirt and sell it, I can get in trouble for violating trademark. If I take a still frame from Steamboat Willie or Fantasia and photographically print it on a shirt, I could potentially get in trouble for violating both copyright and trademark (though the copyright case might be debatable).
In a few years time, I will, if I like, be allowed to sell DVDs of Steamboat Willie and post it on YouTube, and Disney won’t be able to do a thing about it. But I still won’t be able to do that with Fantasia, since it’ll still be under copyright for however many more years. And I still won’t be able to sell the shirts (whether printed or drawn), because those will still be trademark violations.
I imagine that Disney’s lawyers are going to have their hands full in the next few years with people who don’t understand this distinction.