My expectation is that a lot more customization based on fares is on the way. Another recent topic in this subforum has already been hinting towards that. Booking/fare class as the sole discriminator of service and restrictions is absolutely a thing of the past.

See the remark above. I don't think a project like this wouldn't generate enough interest. I do believe, however, that it cannot be done without requiring significant surcharges and/or membership fees, especially if a 24/7 support desk and some guarantee against debit memos are required. So yes, that makes it DOA in today's day and age. Same reason why the consumer TA market has been reduced to a few consolidated players.

Note back in the day - before the internet went into "dumbing down" mode - you could actually register as your own personal travel agent through some of the bigger players and have access to a console ticketing interface. Tickets issued through that interface would bear the IATA number of the big player and they would just invoice you every month for what you purchased. There are still some topics about that dating from the early days of FT.