That's actually not true. The new launcher will allow you to use older versions (as early as 1.5.1, at this point) and it'll also allow you to create profiles, which I've personally used to create a specific "Creeper's Lab" profile (which is currently set to play the game at 1.5.2, and which I'll change when the server updates)

Of course, you -can- still use the old launcher, and for some, that may be easier for now, but at some point, the new launcher will need to be updated.

1.6.2, actually. And no, I don't have any further information on this. The server update becomes available without warning, so I'll simply wake up one morning, see that it's available, then start planning things accordingly!