One one hand, yes it seems that game last less now, but that is more the fault of the players for not keeping them alive, by supporting the game that in theory they like/love
A game lives as long as there are people willing to play it, that is why games like ST have been around for many years.
On the other, there isn't a problem if we can get options that are similar and more importantly, are good.
Plus game companies don't benefit from the players playing the same game for long times, they benefit from the players buying their new games, and hopefully attracting more people to them.
That is why making new games can help to bring a new player base that were not interested on the previous one, but find something appealing on this new option, this could lead to them getting in on previous games that they passed because they weren't interested at that time or were not aware of.
So as long as the scene works to keep the game alive, the influx of new players because of new games could learn and get interested on them
Sorry for the long post