Either the original path is remembered while forwarding, and reused while accumulating results, or certain nodes within the web could take on greater responsibility to manage forwarding and accumulation. The latter seems to make more sense and be more scalable since many paths might just be enroute to better or worse places and should not be held fully accountable just for having provided a link. These remote centers would specialize in various topic areas or search techniques. Paths to valuable centers should be shortened by providing short cuts rather than only strengthened. But instead of merely being iterative, which assumes centralized control, we also have asynchronous queries which pass on control to the next node and let that node relay the results back to the originator, or pass on control to yet another node.
Hierarchy is still appropriate sometimes, but delegation is also important.
A more condensed version of some of the above ideas is my position paper , and slides for a presentation , for a W3C Distributed Indexing and Searching workshop.