If Matchpool is well executed, I believe it has the potential to reach the size of STEEM and probably even outgrow it in case of big success.
Steem currently has a marketcap of 300 million USD. If Matchpool would reach that kind of marketcap we would be looking at a 3000% increase or x30 and a GUP price of over 4$.

If Matchpool is poorly executed people won't give it any interest and it will be abandoned and worthless.

So far the team looks quite good and the potential is there. Wait and see.
Considering that Steem launched in March 2016, it will probably take about two years from now to truly evaluate the success of the Matchpool project.