I'd doubt they would be too concerned as to savegame formats as pretty much all areas are exposed with the editor that they have currently provided. I would very much doubt there would be a rash of programs if it were opened up, especially since anyone intereseted in the formet could simply work on the open source project.
I'd be very keen on an open source project as long as it was ratified by SI, since it still is their IP that is being datamined. I've found great use in using FMScout and MCM in the past to get searches that were impossible in CM/FM. They all have their limitations though, as fairly standard questions that I would like to ask are still impossible to do:
"Give me a list of all people that are coming out of contract protection in the next week", "Give me a list of people unsettled at their club", "give me a list of youngsters that have entered the system since my last search", "Rank my shortlist by pace, 3/4 dribbling, 3/4 crossing"
The new multiple conditional search is great, but a self proclaimed infoholic like me would love to aim some SQL statements at the data to extract exactly the people I'm currently interested in. At the moment I'm happy with the level of hidden data, even if it means I have to have 10 scouts 'filling in the blanks' for me. It's when I want to filter the list to a smaller subset is when I start reaching for MCM.
/me puts his hand up for open source