I'm thinking another option for JetBlue might be Gate 22. Back in 1999, when ABIA opened to passenger traffic, CO was only leasing Gates 16 & 18 and flew to EWR and IAH. At some point in time, when they added CLE, I think, they leased a third gate, Gate 22. Based on upcoming flight cuts, CO may no longer need Gate 22 and it's just across the concourse and one gate down from JetBlue's current gate.
I went here:
http://timetables.oag.com/aus/
and compared CO's July 23, 2008 (pre flight-cuts) schedule to their September 23, (post flight-cuts) schedule.
Currently Contintal flies 2 X CLE, 3 X EWR and 11 X IAH for a total of 16 daily departures. In September, they drop the 2 CLE flights, keep the 3 EWR flights and reduce the IAH flights from 11 to 9 for a total of 12 daily departures. I would think they could run 12 flights out of 2 gates and if so, they might consider sub-leasing Gate 22 to JetBlue. Just a thought.
Maybe I'm wrong, but I really feel (hope?) that in spite of fuel prices, JetBlue wouldn't hesitate to add a few additional AUS departures if only they could get more gate space.