the series will only be around for possibly 3 more games after skyrim,
Do you have some reason for thinking there will be only 3 more games after Skyrim? Or are you just pulling numbers out of the air? Explain.
Another option is as long as Todd Howard is alive and kicking...
The Elder Scrolls series was around well before Bethesda hired Todd Howard and there's no reason to believe the Elder Scrolls won't be around long after Todd Howard leaves to work for another company or is fired.
As long as people continue to buy enough copies of the games to make the series profitable the Elder Scrolls series will most likely continue.