I think he's saber rattling, but then again he just might use the nuclear option he whined about when he wasn't majority leader pre-2007.
It's not a good idea. The GOP's chances of taking his leadership from him have gone from slim to some.
Without a filibuster Obamacare, though fully implemented, could be (and probably would be) done as we know it in 2017 if the GOP takes full control of the government back...also a growing possibility.
It could work out to the Dems benefit, unless they've got a special DeLorean somewhere and they know something (heck, I'll take them knowing anything at this point) we don't know then they should be careful of what they wish for.