If D&D Beyond kill the sale of print books and WotC buys the company behind D&D Beyond, then I can imagine print books being removed.
D&D Beyond is produced by Curse. Curse is owned by Twitch. Twitch is owned by Amazon.
Hasbro is not buying Amazon.
Interestingly, Amazon sells a lot of D&D books.
Basically, D&D is on a path to one company have monopoly power over the distribution of their product. It's probably not alone in this.
Books are not going away in our lifetimes. A lot of books are still sold, just through fewer retailers. And the tactile pleasure of a book is something that can't be replicated in any other medium. (Unlike, say, a film--which gives you more or less the same experience on VHS, DVD, or streaming on Netflix.) However, none of that is a guarantee that D&D will continue to print and publish books.
As to the original question...I think there will be a 6E for the 50th anniversary, backward compatible with 5E. It'll be a 1E to 2E or 3E to 3.5E evolution. But. I hope I'm wrong and that 5E lasts a few more years beyond that.
Final thought: a successful movie won't have significant impact on sales of the game. Marvel comics enjoyed a slight bump as the movie's grew in popularity, but are currently in a downward turn. The comics are basically raw material for the MCU to mine (and they do a great job of it). Hopefully, a D&D cinematic universe can be just as savvy and successful. But TTRPGs will always be a niche hobby.