Is this a sign of the end of Add-ons for Skyrim or just fixing an oops with the first strategy guide?

The devs said they were coming out with another dlc so I doubt its because they aren't making any more dlcs.

Oblivion had a similar revised guide that covered Knights of the Nine, Shivering Isles and etc., after the original one just covered the vanilla game. It's nothing new. It's quite possible that there will be another guide down the road that covers any possible future dlc.