There's no point in saying to buff him for future bosses...just wait until the new bosses come. You do not know how powerful they will be. If you are going to take the hypothetical route and base your suggestions off of unknown bosses, then take for instance a new boss that is a trillion times tougher than Azazoth, then at which point, your suggestion of 100x crit would be meaningless since 100x of current possible damage would not even scratch him. Obviously, when new bosses come, heroes will be buffed/debuffed as need be. The only thing you can base buffing or debuffing suggestions on are current relative comparisons to other heroes and their supposed roles/class. So, let's take a look at the tank (RG) versus the dpser (PR). The ratio of PR's damage output compared to RG's damage output is high enough.
Now, let's take a look at the ratio of PR's damage intake versus RG's damage intake. Is it the same as the damage output ratio? Should we make it the same? Those are the balancing questions and decisions you should focus on...not hypothetical situations of future bosses.