Great question!

The whole calculation for the "convergent linear" rewards is based on rshares which are generated by the voting SP. So yes, when the value of steem rises, this $ figure will rise with it. There's some more variables in play of course, but basically that's it.

I only used the $2.50 here to illustrate the situation in present conditions. because speaking about X trillion rshares on a post doesn't really mean much to anyone, but if the value of steem drastically changes until the fork flips, then this post will be accordingly inaccurate by then, too. Actually it's already a bit inaccurate, I did my calculations a few days ago when steem was more like 20ct still ;)