Not advocating either stance here, just giving information:
We would have to prematurely end some stories, but not all as it would take one to two years to convert. So we would have time to wrap of some things, perhaps 40-50%.
For those of you who like epic level adventures, a switch would decrease those, as we are now just getting in to some of them in the current campaigns.
It may seem early to address this, however, this sort of change would require years of preparation on my part, so the sooner I know, the better.