I think the only conclusion to draw is that the sort of optimism that emerged in the period just after the Portsmouth Petition wasn't sustainable, although the end result was a situation in which the principals couldn't even continue to express themselves in a public forum.
I would tend to go one step beyond this and suggest that Anglo-Catholicism is such an elusive entity -- indeed, with exceptions, primarily an illusion -- that it wasn't a good project for Rome to try to bring elements of it into the Church, especially in light of the numbers of cradle Catholics who've abandoned, or been abandoned by, the Church.