This thought just crossed my mind while reading another thread on the issue. I haven't seen it mentioned before but if it has my apologies.
ZOS has acknowledged there are balance problems between magicka based builds vs stamina based builds. I consider that an accepted fact at this point. The question is figuring out how to fix the problem. The most frequent reason provided for why stamina based builds are at a disadvantage is because block, dodge, and interrupt use stamina which reduces the amount of stamina available to use for weapon attacks.
The simplest solution is often the best solution so I think the following is a simple solution to solve the imbalance problem: Whatever weapon you have equipped determines what resource pool that block, dodge, and interrupt draw from.
For melee weapons nothing would change. For destro and resto staff users, they would have to use their magicka pools to perform those activities. Since some of the magicka would be used for blocking, dodging and interrupts, that means less magicka available for using abilities and weapon skills. The end result is that both magicka and stamina based builds would be brought to the same level.
Sprint would remain a stamina activity regardless of what weapon is equipped.