Blesta won't replace WHMCS. It's been around too long, and is nowhere near as feature competent as WHMCS.
Yes, they can adjust their reseler pricing, but they still suffer from the same problem WHMCS does... NOT listening to clients, and not adding features necessary.
It's going to take someone absolutely new in this business, just like WHMCS was, to take the industry by storm, and then take over. Blesta's had it's opportunity, it's not going to overtake WHMCS.
Don't get me wrong, Blesta is great for keeping WHMCS somewhat honest, as a second place competitor, but after 10 years, that's all it's ever going to be, second place.