I believe 1-2 years is too long between raising of the caps... 6 months every 5 ranks would be sufficient, constantly giving new content for these new ranks... People don't get stuck on their equipment, because it didn't take 5 years to get it, and the game gets new challenges, new abilities and more possibilities... It also helps create a sense of accomplishment as there will always be something else to achieve. Leaving the cap at a fixed number eventually means people leave once they cap out and get all they want. Nothing else to do...