Funny, looking at the TA payscales I see that 717 Captain pays about $50 per hour MORE than you're current aircraft/position. As the block hour ratio would require 30-40 more mainline aircraft at worst case endstate (planned DCI shrinkage) that means your premise is invalid.

Again, there are no guarantees of growth, but the downside protections are far better if the shrinkage you presume actually happens.