At best, it will be just a continuation of MS's old "come talk to us" thing where if you want to thrive on the platform you will need MS to put you on the service. With the focus on GP, it leaves little oxygen for indies that want to go with the traditional model of "make game, sell game to people" and everything becomes "doing it for the exposure" when you arent one of the big dogs.
At worst, third party games start being designed around the fact consumers dont pay an entry fee for their games and F2P-like models proliferate (possibly even to other platforms) as a result.
And all you have to do is look at the current streaming situation in film/tv to see where this ends up. Major services bidding for exclusive rights to franchises/games/pubs and major pubs simply breaking off and starting their own service and taking their games with them, fracturing libraries across multiple services. Eventually, it will be wayyyyy too expensive to license huge titles and these services will go back to focusing on their owned IP and content
At worst, third party games start being designed around the fact consumers dont pay an entry fee for their games and F2P-like models proliferate (possibly even to other platforms) as a result.
And all you have to do is look at the current streaming situation in film/tv to see where this ends up. Major services bidding for exclusive rights to franchises/games/pubs and major pubs simply breaking off and starting their own service and taking their games with them, fracturing libraries across multiple services. Eventually, it will be wayyyyy too expensive to license huge titles and these services will go back to focusing on their owned IP and content