I think there is a good chance it could be. After all it will involve members of the original cast, and John Stamos who starred in the original show is directing it. I like the idea of taking the show into the future, for me that is better then lets do a remake trying to erase the original show off the map, this I don't like too much.
Even if the Olsen twins commit to doing the remake, the original "Full House" was so good, the remake can't be better. The Olsen twins are also no where near as cute as they were when they were children and that was a huge draw of the show. Bob Saget hasn't committed to the project either. Without all three of them, "Fuller House" might even be a big flop.
You just don't have the same dynamics between the characters. The actors have all changed over the years. They aren't the same people, and it will feel forced if they are trying to make their characters the same people when they should have changed over time in their fictional world. The girls are grown up, but we didn't get to see them grow up, and the time spent explaining the past in the first few episodes might result in conversations real people would never have in an effort to update the audience. The result will inevitably be a loss of continuity that just won't be satisfying to the audience.
No, Fuller House can't be as good as Full House because spin-offs and remakes are rarely as good as the original. I'm not saying it can't be good, but it can't be as good or better. Remakes and spin-offs can be good, but they can never recreate the magic that the original had.