That's a big problem for the future of hockey in Trenton. I'm not sure the market would support an AHL team unless it's the Phantoms. The Devils AHL team wouldn't draw significantly better than the ECHL team - would Devils fans come to watch future NHL players? Maybe. But the same folks that stayed away from the ECHL club because of how it was operated would stay away from the AHL team for the same reasons.
I think the Phantoms would be a huge draw in Trenton - from the existing fanbase of former Titans fans, the local Devils fans aching for hockey, and former Phantoms fans from Bucks County that would flock to see the Flyers AHL prospects. Honestly, priced appropriately, if such a club averaged under 5,000 I'd be stunned.
That said, it's a longshot at this point that Allentown doesn't work out - once they start the eminent domain process for the land for the arena, they're probably fully committed.