I can't imagine that Amazon would ever want to deal directly with pilots' unions. And have only one basket for its eggs. So it makes no sense.
In the recent go-round, various carrier/Amazon contracts were expanded and extended. I would expect that to happen in the future if everything continues to work well. The original contracts were executed at a time that nobody had any idea whether this would work, so there were lots of provisions structured with that in mind. They don't mean anything in today's situation.
As to the retention bonuses, however, to me they're concerning. They usually arise to keep the current hands on the tiller where there is a significant likelihood of some kind of meaningful challenge -- operational, financial, etc, where something's likely to happen that might incline one or more of the experienced hands to bail before the other shoe drops. These kind of agreements are disfavored in bankruptcy, but not uncommon in highly-challenging times that might eventually lead to bankruptcy. Also not uncommon where a company is going to break up, sell off pieces, or otherwise reorganize outside of bankruptcy.
The executives know they're gonna get wet if they stay in the boat, and don't want stink on them if the thing fails, so, Men of Great Courage that they are, many bail before the rapids and these kind of agreements are designed to keep them in the boat.
Here, I'm not clear what the deal is. Maybe they want to monetize the leasing business by selling it off to someone like a GECAS, or maybe private equity. You know how Wall Street douchebags often want to do these types of transactions under an assertion that one can "unlock the value" of component pieces of an integrated business. These often come to tears of course. But the Wall Street guys get plenty of $$ from the process.
Or, maybe they're concerned that when the NTSB report comes out it is going to castigate parts of the operation such that a major customer like AMC is forced to flee. (And AMC can certainly transition to other carriers. The generals love 747s, but they can do all sorts of things to make another carrier a viable substutute provider over time. 777s and 767s for pax at Omni. 747s and 777s and 767s for Cargo at Kalitta. Maybe even new business lines at carriers. ATI has flight attendants and the specs to carry pax, for example, and operates 767s. It's all doable.) That would be a big hit.
So maybe the execs are preparing for that kind of turbulence ahead. I might even give those "These kinds of things might happen in the future" disclaimers in the financial statements a scrub to see if there's anything new in there; they're generally like the Book of Revelations as far as being able to be interpreted to mean anything, but that could be an interesting exercise and food for thought.