You never know when the boom will end. Depending on how you look at this, it can be good or bad.

My take, for what it's worth. Get a degree. I don't think it would be very easy to complete an online degree while on the low end of the seniority list. Instrucing while your complete a degree is going to give you tons of options upon graduation. You'll have more hours so you'll be more competative, and you'll have more options. Choose the regional you want to work at for a while, not the one that will take you first.

What happens when you don't have that degree, and you're ready to move up to the majors? Most require a 4 year.

Barring something catastrophic, this boom isn't going anywhere anytime soon. The shortage at the regional level is only going to get worse as the majors start hiring more. You may help yourself in the short term by getting in now and getting seniority. However, your career will have no upward mobility if you elect not to and you have the other requirements met.