yeah but you know what would suck is if destiny 3 came out on some other PC platform and any veteran-style rewards were simply unavailable to people who played destiny 2 on PC due to the platform switch
oh wait that's exactly what happened to people who played destiny 1 on console and moved to PC for destiny 2, no veteran rewards for anyone on PC even though you are able to link your PSN/XBL profile to battle.net. bungie knows if you did stuff in D1 on PS4/XB1 but couldn't be bothered to reward you for it if you decided to play D2 on PC.
We really don't know what sort of deal Bungie and Activision made to let them basically walk out with the IP. For all we know, Activision is still making money off D2 and will. Which is why they didn't throw a fit and are keeping the game on Battle.net.
D3, well that's going to be a different story. I doubt it would be on the Epic Games Store, mainly due to what the game needs. As it is now and until Epic says otherwise, the service won't be offering game servers. Steam not only has their own game servers but recently said that usage of those servers will be free or discounted.
Of course, that's all down the line. Hell, Bungie could set up their infrastructure and run it themselves. Who knows. But if they do, can I get hired there ;)