I have a (not completely comprehensive) table upgrade guide here: https://github.com/c...e-Upgrade-Guide
Most of the stuff is pretty trivial (changing some parameters in an easy way, renaming some script functions, etc.) and could maybe be done by a tool. Someone would have to write that tool though, it would take some effort and it could still mess up since it has to change the script. A dedicated table author could probably do all this stuff in 1-2h for one of his tables.
Then some parts are a bit harder, especially the changes for the new physics engine. I have it on good authority though (Uncle Willy said so) that the new physics engine makes it much easier to get good results than the old one, and with much less tweaking. So again, it shouldn't be that bad.
There's also the changes for the new lights; I don't know how much work that is, but I think once the new supporting script functions are written, which has to be done only once, it will be pretty easy.
All in all I would estimate that a table author can upgrade a table in an afternoon or so once he has some experience with the new version. That's not taking advantage of any new graphical features, so the table will look more or less like in VP9, but will benefit from the new physics. So I hope that we will see a reasonable number of VP10 tables relatively early on.