I just sold my Canon and ready to buy XE1 this week. I think the upgrade you mentioned on X100s and X20 would not apply to Xe1 family line because the 100S and X20 are changing to Xtran sensor. It shows Fuji has a lot of confidence in their sensor now. The next in-line would probably be a refresh on Xpro1 - maybe a silver version, that is my guess.
I do however caution on the choice of lenses for XE1. Right now, more lenses are coming out within the next few months, another 55-200 Fuji zoom (USD699) and a new line of fixed focus from Zeiss (with auto-focus!)
I think the same bet is to get XE1 with 18-55 and wait and see what is coming, that is my present strategy, hope it is helpful!