It simply isn't possible to make progress in the other direction. Once scope is gone, it's gone for good unless you have some way of creating a one-list with your regional feeders. DAL now has 10 DCI feeders, so a one-list is no longer an option for DAL. If DALPA attempted to "take back" scope, then Dan Ford would file lawsuits about DALPA "stealing" his flying. Another RJDC mess would ensue. Holding onto current scope is about as good as anyone can hope for.
Sure he could sue, but so what? He would never win. And the regionals gave up any claim to seat specific scope when they agreed to fly 70-90+ seat jets for at or extremely close to 50 seat pay. But if DF's lawsuits were nevertheless a concern, there are ways around that.
For example, every ALPA legacy outsources plenty of flying to non ALPA carriers. They could first reclaim
that flying. Then they could reclaim all flying from ALPA regionals slowly through attrition (thus causing no furloughs). That process could be accelerated and mitigated by hiring exclusively from the ALPA regionals until all the flying was brought in house.
No carrier can expect ALPA to guarantee other ALPA carriers forever allow their code to be outsourced. With each contract and side letter comes the chance that outsourcing could be increased, decreased or eliminated. Every ALPA pilot group has the right to dictate the terms of their flying to their management. An amicable one list scenario would be preferrable, but if RJ pilots demanded mainline seniority (which many in power, like DF, most certainlly would) then other means would be available.
Take Delta again for example. DALPA could force the elimination of all SKYW and CHQ flying and force management to hire exclusively ALPA pilot groups (something all ALPA scope clauses should contain anyway) and all jets above 50 seats. That would force massive ammounts of flying to ASA, Comair and Pinnacle. For every 70 and 90 seater that was removed from an ALPA regional, it would be replaced by at least one 50 seater, probably more. The miniscule pay difference (the only other potential "harm" to ALPA groups) could be paid for out of the ALPA kitty. What are we talking about, a couple bucks an hour primarilly for the Captain seats only? If that's career dammaging then fine, reimburse them but take those airframes back.
AA wouldn't have a care in the world because they have their own union.
CAL doesn't allow any jet over 50 seats anyway.
UAL primarily subs to non ALPA carriers.
If SWA is dumb enough to outsource jets to anyone, they will likewise be 100% theirs to reclaim at their liesure at any time.
USAir could still do it if they remained ALPA by ALPA paying the miniscule pay differential to Mesa, PSA, etc. If USAir leaves ALPA and certifies USAPA they could just do it at will.
That leaves only NWA, and most is not all their large jets are going to Compass anyway, which is already controlled by the NWA MEC isn't it?
Again, all this couldn't be done in one day, but it could and should be started immediately. If its not reversable then eventually MESA will be flying 777's for DAL, UAL, etc. The "line in the sand" is 76 seats installed, but next downturn (which may already be here) some knucklehead pilot group will allow max certifiable. Then the CRJ1000 and E175, 190 and 195 max certifiable. Then small 737's and 318's, since they seat the same afterall. Then the big 737's and 320/321's because the regionals already operate that overall type, etc etc etc.