Bethesda said from the beginning that ESO isn't the end of the series. Zenimax Online developed this. The game takes place a 1000 years before skyrim and 800 years before oblivion.
Todd Howard himself recently said in an interview that if a new Elder Scrolls would be announced it would take place after Skyrim. Most of Bethesda and Zenimax treat ESO as a prequel. Most of the lore in the SP games, you experience in ESO. Tiber septim (Talos) is not born yet, he is known for uniting Tamriel after an inredibly long war, which is the PVP in ESO.
The alliances are also mentioned in lore with the most recent being the Aldmeri dominion which has been reastablished years before Skyrim takes place.
The Ebonheart pact defeats the akaviri invasion, which in Oblivion involves an entire quest line to find an abandoned fort.
Todd Howard also mentioned that if a new Elder Scrolls will be made it would probably be on of the biggest SP adventure games they have ever made.
Bethesda would never drop the Elder Scrolls, since it's the first series they ever developed and released.