Okay, I'll give you some current data if it makes you feel better. Please understand that things are changing unbelievable fast around here. This data will look completely different after the latest bid closes tomorrow and is processed. And things will look completely different in a few months after that, and so on... I know you're wondering how thing will look in 1.5-2 years, but you could take a guess on how senior each base will be that far out from now and your guess would be just as good as ours. But again, if it makes you feel better, the current stats for seniority per base/equipment (valid for a few more days) is:

Most Jr DFW 175 FO: 10/2017
Most Jr DFW 145 FO: 05/2017

Most Jr DFW 175 CA: 01/2016
Most Jr DFW 145 CA: 12/2016

So there it is, the current snapshot. But you simply cannot use these numbers to make any kind of guess on how things will look 2 years from now. There is far too much change ahead and variables. For example, you might say "Hey DFW 175 FO is pretty junior". Yeah, well that was probably the last new hire class that went directly into that status that we'll see for a very long time. So each month it will keep getting more senior and more senior. Then you have the forced upgrades throwing a huge curveball into the seniority. Then you're gonna have more and more senior FOs displacing into different equipment and bumping junior guys out. So on and so forth. But anyway, those are the current numbers. Just know that they are completely useless figures for trying to make any determination for anything as far out as you're looking. The only semi educated guess you can make is that DFW will remain to be the senior base. How senior, that's the unknown.