If the older packages have badly written dependencies, they might very well complain. Or it might actually be the case that they depend so heavily on a specific version of Qt that it's not going to work anyways using Qt4.6.

What you should do is investigate which Qt packages you actually have installed. If the new ones replaced the old ones, you either wait for updated packages that depends on the new packages or figure out how to install the old ones alongside the new ones.

It's misleading to blame the new PR since dependencies are written by the individual application developers. However, if anyone from Nokia has promised that older Qt applications should work, you have reason to blame the PR.