Videogame trademarks are a weird thing, sony has used the name enough in press and announced a game with it already that they don't urgently need to renew it.
If anyone tried to file the trademark that sony let lapse, they could easily get it back by filing a complaint that another person/company was doing so 'in bad faith'.
(It costs about about 2k USD including legal fees to do a filing, 1K EUR to do a separate filing that covers EU and UK territory) and that's just to cover the category of 'videogames'.
Trademark filings get more expensive the more categories they cover (if its trying to be used in books and more broad categories of merchandising and media)
I'm somewhat familiar with all this cause I have an attorney that handles all that kinda junk for my business.
Its common for smaller developers to not file a trademark until closer to release due to the protection afforded by announcing your game through press release to have grounds for defending against bad faith trademark filings. Filing trademarks too early can also be a moneytoss in the case of you rebranding and renaming the game which would require another application+attorney fees.
Obviously sony is not small and several thousand dollars is nothing to them, its hard to say what will happen based on the trademark just lapsing.