Once you've rooted, Vice City works just fine. San Andreas is currently not available rooted or unrooted but Rockstar's developer has it working fine on M.O.J.O. so we're just waiting for them to enable it.
The price is absolutely correct for the level of hardware that you're getting in M.O.J.O.. Remember that if you're comparing with other Android consoles released so far you're not comparing like with like: they're using older chipsets that are less powerful by at least a factor of five. Even if you compare with an Android phone, as some do, there's still a distortion there in terms of price expectation - sure, I can get a Galaxy S4 for around £100 if I go for a 2 year contract, but if I want to buy one sim-free then you're looking at something more like £420. Either way you do end up paying for the phone somehow!
Plus you're getting the best Bluetooth game controller available today when you get one.
If you want a powerful Android-based console that the community are already starting to open up to then M.O.J.O. is it and with more great features on the way (such as Gamestream) it's a box that's only going to get even better. So to answer your final question (and also question 2), we think there is definitely a future for Android consoles, which is why we're here with M.O.J.O..