It would seem the Eagle Single has been a decent STC. Although their timing was probably a little unfortunate considering the GFC.
Perhaps if bell put the soft-in-plane head and some of the EP upgrades to that engine (or a single PT6-67C), they would have a great alternative to the 205's and 212's without a lot of R&D.
Secondly, I'd love to see a wider cabin, flat floored 407 with something like a HTS900 to really compete with the AS350's (IMHO where Bell has been so lacking in the last 20 years)