Aldo has only lost to rangy out-fighters, his game and style is built to eat up stocky wrestlers that lunge into the pocket throwing power shots.
The physical decline on Aldo is real but it looks to be more cardio/endurance then speed, so in a 3 round fight I think he can bank on not having to conserve energy as much. Volk is a legit contender though, dude has tenacity and heart but lets be real - his last wins are against Chad Mendes (coming back from multi-year layoff, retired right after), Darren Elkins (grappler with no striking defense) and Jeremy Kennedy (who???).
Meanwhile Aldo has been body-bagging dudes like Jeremy Stephens and Renato Moicano, so this is a a big step up in competition for Volk, while Aldo gets to fight a stylistically favorable match-up against a style/fighter he's seen before (Volk is similar to Mendes in many regards i.e. build and style....not as much wrestling skill or counter-ability but better pressure, more volume, more chin + heart at this stage of the game).
Close fight but Aldo by decision is my pick.
