I think you are saying that the incentive for creating new games is reduced when so many old games exist.
The evidence isn't the lack of new games but the forever game series - gta, cod, fallout, assassin's creed and so on and so on - games which win attention and profits get endless follow ons
The aim, and it has been partially achieved, is for games to be like netflix - something you subscribe to, play while available, subject to constant updates, completely lose when its dropped
In the middle of all that there has been much analysis, like with social media, as to how to keep people playing - a constant flow of new features, endless new 'quests' and 'loot' and micro transactions to build in-game abilities and access certain features
and then there is the slow decline in the notion of games machine / console - at some point why n ot just do everything server side and simple stream the game at you - where all you need is input/output - a bit like netflix again.
finally there will be ai generated content to enhance variety and fine tune the 'marketing' to you personally
so there is plenty of incentive still, its just not geared to making "new games" in the way i think was meant in the question
meanwhile, out there, there are lots of interesting, often indie developed games, that do take risks and provide something new - at least that seems to be thriving still