Unless im missing something, the Prevail never received ICS or JB, meaning there is 0% chance of anything newer.
The Prevail is out of production and hit the "clearance bins" six months ago.
The only way for the Prevail to get 4.0+ is for a privateer to reverse engineer from existing code, and that is extensive work with only a "pat on the back" type reward. It can take a development team months to port an iteration of Android to a phone so why would a privateer do it for free to a phone slowly losing user base?