We wont know much either way until the 2.0 is closer to release.

They could just be tracking our character data and converting it over over the course of a few weeks before 2.0

(Warning any progress beyond this point doesn't matter character data is being converted from ___date.)

Or the game will smoothly translate into the new engine, and our character data will read in the new engine as it did in the old. It's a rather technical question and I doubt we will really know until 2.0. On another note SE only stated out character progress will be retained they haven't said anything about items/money have they?