Sony will not go after anyone using Let's Play in their Youtube videos because that would be counter-productive. The last thing Sony wants is a reason for the media to constantly go on about how Sony are monopolising the industry. The is probably a new service coming to the PS4 or perhaps an actual game, but the benefits of using Let's Play isn't in the ability to control the name, it's in the name itself. There are now millions of people watching Let's Plays on Ustream, Twitch, Youtube etc. Once Sony get this trademarked and after it's released (whenever that is) then anyone searching for Let's Play will also come across Sony's version of Let's Play. It keeps the term high in the rankings of search engines like Google. With that in mind I'm convinced that Let's Play is going to be something big enough to warrant that extra media attention.
The PS5 Exists.
