TESO designers made it clear that the timeline was chosen for this game to set it apart and not put any restrictions on what gamesas does with the single player series, but they will restrict the single player games in another way.

Places like Summerset Isle, Elsweyr, and Black Marsh etc are all being designed and mapped out for the *first time* by Zenimax Online, not gamesas. I'm talking building archetecture, map scale, terrain etc. To maintain continuity gamesas will have to take these design elements into account for any future single player games just as much as Zenimax Online had to take the design of ES 3, 4, and 5 into account for TESO, and they will not really be free to design these provinces as they might want.

Just as a disclaimer - I had always thought there would be an ESO, but I'd thought it would be set on Akavir for this very reason. Perhaps the single player games will move to Akavir instead?

Considering the changes made to Cyrodiil in Oblivion, I don't think solid continuity between Beth and Zenimax is going to matter that much. It certainly didn't even between installments of the Elder Scrolls.

You are thinking way to much into this

they are working closely with Bethesda and Todd Howard himself to help ensure they don't restrict the single player games. I think Todd has to sign off on any major decisions pertaining to the franchise. they arent just given free reign. zenimax/bethesda both know butchering the franchise would be a huge mistake.

Two studios.

One lore.

Even so, over a thousand years has passed from this game to skyrim, much changes.. even if they altar design it could change over time. no worries