I want to heavily prune or get rid of an old highbush cranberry that has issues....insects, disease? I’m not sure it’s worth hanging onto. One side of it died over the winter, too. Can you tell me what’s going on with it and if I choose to replace it, can you recommend a different native shrub for that sunny area? Thanks
The leaves in the photograph you sent appear to be eaten by insects. The viburnum leaf beetle does such skeletonization:
If that is the plant's only problem, it will probably recover. But you mention dieback. This winter might have weakened the plant (and the insect predation then followed).
If you want to keep the plant (it is a native, by the way), I'd suggest you do a rejuvenation pruning. Prune out 1/3 of the plant down to the ground, starting next winter. Then repeat for two more winters. Your cranberry should look like new after that.
I would not start this process now - make sure it gets proper water so it can regain some vigor this summer. Read here in this Ask Extension answer: