It would have been manageable : Low Countries were providing with important fiscal entries and HRE would still have access to important loans even without metallic entries to repay them trough thesaurisation.
It doesn't mean that Hapsburgs would have a same budgetary freedom than IOTL, and it might lead to relatively more political compromise than IOTL, but French presence in Italy still pretty much favor an imperial-Spanish alliance (even if Valois have more chances ITTL to hold on Milan) while a lesser HRE's threat might prevent a bit of the general anti-Charles V front that existed IOTL.
It doesn't mean that Hapsburgs would have a same budgetary freedom than IOTL, and it might lead to relatively more political compromise than IOTL, but French presence in Italy still pretty much favor an imperial-Spanish alliance (even if Valois have more chances ITTL to hold on Milan) while a lesser HRE's threat might prevent a bit of the general anti-Charles V front that existed IOTL.