I wouldn't put it past this management to just schedule this flying because it can. In absence of a new JCBA and new scope clause, the company will take advantage of every loop hole it can.
The CAL contract defines the 50-seat limit. The UAL contract allows bigger jets. This will be done under United Express banner out of current CAL (I know they are all United) hubs.
The company also knows that if a JCBA becomes effective Jan 1, 2011, as an example, that the 70-seat RJs will not turn into pumpkins on Dec 31, 2010 @ 23:59:59. It simply won't happen as that is the reality of Express contracts that the negotiators and reps are well aware of.