Your last question is a bit loaded with a bunch of "ifs", so let's unwind it. I don't know what MongoDB will "support" as far as other engines go. But assuming we, Tokutek, release something that we support that is our engine plugged into 2.8 using MongoDB's storage engine plugin, then according to the design we heard about at MongoDBWorld, that product will be what you think it is: Mongo with geo and "other bells", and TokuMX's compression + write performance.
But 2.8 is a bit away and the storage engine API is a very fresh development. I don't think anyone is in a position to be able to really guarantee what it would look like and how TokuFT (https://github.com/Tokutek/ft-index/) will plug into it. I definitely cannot make any promises.
If you are interested in TokuMX + some missing features from MongoDB (sounds like geo), and don't mind discussing your needs and use cases with our sales guys, please give us feedback at http://www.tokutek.com/contact/. As I mentioned previously, user feedback drives what we do, so at the very least, you can provide some additional data points.
But 2.8 is a bit away and the storage engine API is a very fresh development. I don't think anyone is in a position to be able to really guarantee what it would look like and how TokuFT (https://github.com/Tokutek/ft-index/) will plug into it. I definitely cannot make any promises.
If you are interested in TokuMX + some missing features from MongoDB (sounds like geo), and don't mind discussing your needs and use cases with our sales guys, please give us feedback at http://www.tokutek.com/contact/. As I mentioned previously, user feedback drives what we do, so at the very least, you can provide some additional data points.