I’m not sure I follow everything so I’ll respond to the bits that made sense to me.
Offchain resale of tickets could work by having the proposing key generated in a TEE. That way the key can be sent from one TEE to another. With the right proposing_check, you can also just have the proposing key sign the next key and have a TEE guarantee that it won’t also produce a block after that.
Yes, execution tickets more explicitly introduces a (“active”) monopolist, which will surely change market structure.