Discussed at some length here. The backlash will never amount to much, and it's not hard to see why. The Millions did a ranking of Bolaño's corpus. Notable on that list is that, of the nine works listed as "The Essential," six were already published (if in Spanish) at the time of Bolaño's death. One is the novel he was frantically working to complete--there's dispute over exactly how finished 2666 was. One is almost entirely composed of published articles and speeches (Between Parentheses). Only one is new and contains a substantial amount of unpublished material. The other two ranks--"Merely Excellent" and "For Completists Only" contain the slapdash and unpublished material, most of it never intended for publication. Now that the every-six-month discovery of yet another 'unpublished' work is over, things will settle down and more measured judgments may be drawn.
The judgment will eventually be this: Bolaño was a good at assessing the quality of his work. The work he published contains a few weak items--stories and poems, mostly--but is quite strong. The unpublished material is mostly not very good. The problem was not the author but the posthumous guiding of his literary output.
He has a better shot at canonization at most, and the reason is found in the top two books on the Millions list, which are the top two books on everybody's Bolaño list (not mine, but you get the point): 2666 and The Savage Detectives. They are each big, sprawling, and inspiring. Each has its slavish adherents. But aside from the tics of Bolaño's style, they have nothing else in common: one is a writers-writing-about-writing novel with conventional plotting and a slightly askew narrative, the other is political, lacks a narrator, and pulps up genre conventions. That is to say, Bolaño wrote two books which can be considered his most serious, mature work, each of which appeals to a slightly different portion of the people who read literature. Those two books invite the debate they have already received, and that they will generate in years to come. Add into this a novella whose formal excellence is a matter of agreement (By Night in Chile), the obvious influence of the great names of the previous two generations of Spanish-language authors, and the recipe for success is near complete. Bolaño will not have the problem of a David Foster Wallace who, for all his formal inventiveness, wrote one long novel that most people read (but did not finish), which is remarkably different from the fiction environment out of which it emerged, and which produced no literary heirs worth mentioning.
This last will be the key: people have been reading Bolaño. The question is whether anyone will write like him, picking up his thematic interests and narrative tics. This is not an incidental concern: the inability of critical judgments of, say, T.S. Eliot to stabilize has a lot to do with the fact he produced very few followers. If the fiction environment of ten years from now bears his impression, then we can safely assume that everyone's favorite Chilean novelist is at least in the running for a Garcia Marquez-like level of influence.