I think IBKR is probably fairly valued under a reasonable analysis, but I think I can imagine several scenarios where they create new revenue streams that increase their value a lot.
1) maybe market maker stops sucking (I know I know... but maybe)
2) Check the last con call... Covestor acquisition looks real interesting...
3) Scottrade deal looks kind of game changing to me (not necessarily for immediate $$$, but what it represents)
At the end of the day, it's a well run company, that looks (as I've said before) to have a pretty unassailable position. From that safe base, the company is leveraging itself into new areas which could grow for a long time.
Future areas that may increase revenue - speculating on potential changes:
1) Bonds moving from dealer traded to exchange traded - I think this could be huge for IB
2) exchange traded IR Swaps, CDS, etc
3)

It's a great company, run by a smart operator with a history of absolutely killing it with capital allocation. I wouldn't *bet* that amazing stuff will keep coming, but I wouldn't bet against it...
Ben - Still long and strong...