Whatever happens, I expect that there will be a fairly long down period between taking version 1.0 offline and bringing 2.0 online. I'd imagine that moving all of our character and item data over to the 2.0 servers will be a more time-consuming process than the server merge was. Also, the 2.0 announcement page says this:

As part of this process, there will be a period required for switching over to a new client and new servers, after which there will be a large transfer of data when service is brought back online.
It's really hard to tell at this point exactly what will happen when. Maybe we shouldn't speculate, but it's just so much fun.