You've probably got a lot of old growth, but there's likely some younger growth, too, and a good pruning can certainly rejuvenate them. This is from the University of Maine's cooperative extension:

Pruning

Blueberry bushes should be pruned every year to produce high yields of good quality fruit. Prune the plants when they are fully dormant during the late winter or early spring (January through March). For the first two years after planting, simply remove any dead branches and all weak, spindly growth. For plants that have been established for three years or more, follow these steps:

1. Prune out any weak, low-growing or diseased canes.
2. Prune out any canes that are more than six years old (these are usually the thickest canes, which are gray in color with peeling bark). Blueberry canes tend to be less productive once they are more than six years old and should be pruned out in favor of younger, more productive canes. Cut the old canes back to ground level unless new cane growth has been sparse; in which case, leave a four- to eight-inch stub above the ground. New canes may sprout from these stubs.
3. Thin the remaining canes, leaving those with the most vigorous shoot growth (long, thick branches with good fruit buds). Leave six to seven vigorous two- to five-year-old canes and two or three one-year-old canes per bush. A mature blueberry plant should have six to ten healthy canes varying in age from one to six years old.
4. Remove any weak fruiting branches on the remaining canes, especially those less than six inches in length. Most fruit is produced on vigorous one-year-old shoots on healthy two- to five-year-old canes. The fruit buds on these shoots are large and teardrop-shaped. Each bud will produce a cluster of five to eight flowers. The shoots also have smaller, pointed vegetative buds that will produce leaves.

Source:

https://extension.umaine.edu/publications/2253e/#care

In general, I try not to chop out more than a third of a plant in any one pruning, but many varieties will tolerate much harder pruning to renew their vigor.

Here's an article on rejuvenation:

https://www.canr.msu.edu/news/revitalize_blueberries_with_renovation

By the way, you may get more responses if you can edit your post to crosslist in the fruit & orchards forum (you may have to remove the suggestions forum to do it, as I think you're limited to three forums).