Since the 90 day payments stop at the end June, I'd say there's at least a little over 3 months until the Beta starts.
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Roadmap indicates:
"Radical Changes in the game world" in August
"Version 2.0 Software Distribution" on October
"PS3 Beta Test" on what I wildly guess is the second week of november
I'd set PC beta on October, however I do not remember wether they mentioned if the PC beta was coming before the PS3 one but supposedly they will both be running together at some point.
So more like 3 months, yes
Pretty Much Everything that isn't branded dated will follow into 2.0, as much as i hate it. my green mail set that i was one day going to place on a mannequin will never happen.
as for current NM drops and other unique gear like the buccaneers/Templar set may no longer be obtainable come 2.0.
...I'm curious as to how they're going to transition class quests and such into 2.0. They'd all have to be very heavily remodeled and scripted
In Gamerescape's E3 Interview, Yoshi-P says that having such a list is a great idea, so he'll look into having one made up for release around 1.23. We should have at least 1.5 months to play 1.23, so hopefully that's enough time.