It depends, because it may follow the recent pattern we've had, Fall for Japan, Early Spring for the North America, and then about Mid May for the UK, and then the other countries around that time too.
Well they could always recycle some of the amity park overworlds for following pokemon too i guess
I agree, many things were dropped out or change, just like in DP...Amusing, yet strange and weird. Though, yeah a lot of things we see now still have a possibility of change before these games hit the shelves in Japan. The game hasn't been finalized as a completed project and from now until Fall a lot of minor tweaks and changes can be done.
Seeing as the rival is back in again standing in the same position as he was in GSC (yay), I'd like to see more on him (especially given the dialogue from someone in FR/LG about a red-haired kid being Giovanni's son - it is speculated that Silver is that kid). More story and all - he was one of my favourite parts of the game, and made for a more interesting rival than others, like the 3rd gen's May/Brendan.
I have a feeling that only the starters are going to get to follow you, though it'd be nice to see some others being able to follow - but that's wishful thinking...