Do you guys think that Mega Evolution will be the absolute end of the line for Pokemon that didn't have 3-stage evolution lines?

Some part of me wants to believe that some Pokemon, whether single-stages like Pinsir, Heracross, Mawile or Sableye, or two-stages like Gyarados, Houndoom, Manectric or Lucario, will eventually get some 3rd stage evolution, and Mega evolutions will be sort of side-grades...

Is this a false hope? Am I a fool for thinking these Mega evolutions are not the final stage of any Pokemon?