The scalability problem is fortunately amenable to piecemeal solutions. Some research teams will focus on validation (i.e. novel proof of ____ approaches), othe

The scalability problem is fortunately amenable to piecemeal solutions. Some research teams will focus on validation (i.e. novel proof of ____ approaches), others will focus on block propagation, some on bootstrapping (like the OP), novel hash structures for transaction aggregation, etc. It would be difficult to come out with a new approach that simultaneously advanced the state of the art in every possible scalability dimension. Each individual approach might give a 2-10X improvement on that particular aspect, but it also means that the "bottleneck" keeps shifting, and trending towards scalability. Source: I'm an academic blockchain researcher.