i see 3 easy-to.-solve fears
1. computational power. it is a non-issue as long as there is scaling in GFX options available, sooner or later a better HW will come for everyone, i have a 760 and can play, no one need a 3080.... i prefer to buy ammo than to buy a more powerful cpu to kill puny
2. Migration problems.... the solution is TEST SERVER, that replicate player base, you log in (of course TT will give free ammo) and can test everything. nothing come into the production of what is done on test. as the engine is ready, the switch is painless
3. loss of "game experience", well i will not miss the being stuck in water when the coast is too steep, to pass through stones and wall, to have "unreachable" mosnter that have too bad AI to turn around a tree to become targetable, or pets that give undue benefits in mayehm
I see this as a real opportunity to attract new players, and to rework in many places a system that is overcomlicated (we dont need 50 differetn ores, and 50 different enmatters as an example), crafting is useless apart some armatrix models and amps and so on (tes those command component crafting too)
Epic Games playerbase will flow in and?
new players will soon discover that after 20 minutes (or maybe 2 hours) the only "free" activity is sweating (it is not free, its paid by other players) and leave and maybe 1% remain.
so welcome Unreal Engine, but need much more to attract new players and to make them spend 30 usd a month (or 3.000) to keep the servers running