Craig
I agree with your first two
1.) Lionel may not be interested since Mike built so many trains in the past and they will be competing with all those built during the last 10 years with the Lionel name. Folks from Lionel I have talked to in the past felt that they got burned bad by the Hiawatha/Vanderbilt sets - hard to unload, they overbuilt. Maybe with their focus on 'build to order' they may stock stuff and at smaller quantities, but will need to know what will sell. My put: unlikely.
2.) Mike: I talked to him a couple of times about this prior to the announcement of closure but after the 'Lionel Corporation' license ceased. He said first of all that Lionel's price to continue the license agreement was unaffordable. He also said that he would consider limited builds if demand warranted. I suspect he may consider doing that post MTH, as 'he' owns all the tooling that is safely locked away in Chinese hands. My put: possible
3.) There has been talk of former employees taking on some part of the business. For sure they want to do repairs and DCS upgrades and electronics production, as far as new goods, uncertain but possible.
4.) Bachmann has picked up lines in the past (Williams O gauge for example), a weak possibility. Biggest issue is that this is a small market and shrinking, and a lot of stuff will be showing back up in auctions and ebay (recently at elevated prices).
5.) Independent parties: Kuehn bought Lionel (and sold it to another investment group). Needs to have a reasonable business case. Smarter folks than me will think it through. Mike's price will determine how strong that case will be.
I can see availability increasing and prices for older inventory leveling off in the next 1-2 years and starting to fall for all but the most unique and scarce items previously made by MTH (some of the Ives/AF sets, unique paint on 400e's, some eternal favorites like Blue Comet). There are less buyers coming into our hobby for this stuff than those leaving.
Jim