I think that abandoned might not be the exact word I'd use, more that they changed course. I suspect he'd still be asked to be ready for stack duties as well, but that's just a suspicion of mine.
I think that you can't groom everyone forever. The DBs you mentioned are ones that haven't reached free agency yet, so the comparison isn't quite timely. Meanwhile, there seems to be the indirect complaint that we paid an All Pro LB (and team leader) top dollar on a long term contract, hoping he'd remain an All Pro team leader and the crime is that... he has?
But I did say back on a very early page in this thread, that there could be a reasonable debate had as to whether the Saints should have gone with the younger option. I think the team hasn't made a bad choice given what Davis continues to do, just that people are unnecessarily caught up in a desire to say 'woulda shoulda coulda' at Allen.