What if we had 2 seniority numbers? Let's say an airline seniority number and a career seniority. The airline seniority is used for bidding / upgrade / base assignment, etc. and the career seniority is used for pay. I think that is my biggest heartache with the current seniority system is that a pilot who moves loses the gains in pay they've made. Or maybe something like a category of pilot:

Cat A: 1500 - 3000
Cat B: 3001- 5000
Cat C: 5001- 9000
Cat D: 9001 - 15000
Cat E: 15001 - Ohly crap why are you still flying!

If you're a Cat E pilot and move from one airline to another airline you are automatically capped at the highest FO payscale.