I dont care if HL3 (if ever it comes) isnt a groundbreaking game. I just need a good game and thats it! I will be happy if its a good game. It doesnt need to be groundbreaking. If the option is to have a good game vs no game, of course having a good game is a better deal.
Plenty of other good games out there for people to play.
People usually yearn for games from some neglected genre (arcade racers, 3d platformers upto a year or two ago, shmups etc etc).
If it ever gets made Half Life 3 will presumably be a predominantly single player FPS game, a genre that is far from dead despite the rise of multiplayer grindfest fps games.
I fail to see how it's worth giving it any thought, if one isn't expecting it to be head and shoulders above all the other single player fps games in quality and merely "good" is enough.
Honestly, I wonder if in the year 2017, the people still going on about half life 3 even have the faintest idea of what they would expect such a game to bring to the table that wouldn't just result in a backlash against Valve after a decade of non stop memes and forum moaning.
Aside from the money they make from steam etc meaning they don't need to make HL3, if I were valve no way I'd bother making HL3.
People expect them to bring some amazing innovation to one of the most prevelant aaa genres, the first person shooter.
There is a very high chance the resulting fallout from a a HL3 that is "good but not amazing compared to other fps games in 2017 like HL2 was a decade ago" would just damage their brand.