Hello!
Im not sure if this idea has been in somewhere older posts, if so sorry for that.
I was thinking what if each player got his own private island, hosted in cloud or local computer. Only this player can live/build/breed/tame there.
And when player go sailing he could sail to open MMO seas for search rare resources or sell/trade with ppl out there or hunt treasures do quests etc with others even be part of some comppany.
I think this would solve lots of solo/single player problems.