Sony is smart to go with the Bungie style of GaaS. How Destiny 2 started to the game it is today, is like your playing a new game.
The expansions, the seasonal story lines and cash shop. They are great. It's not often I see myself praising a cash shop, but the cash shop in destiny 2 is great. You get a chance to buy stuff using an in game currency and that how I've got most of the things I wanted.
I think Bungie has one of the best GaaS games out, so Sony buying them just for their expertise makes sense to me. If being multiple platform was part of the price for Bungie, then so be it. It's not the ip Sony is specifically interested in anyhow.