They will probably survive but will require corrective pruning for years to get a decent shape back. I'd be seriously tempted to start over with new trees, especially if these are in any sort of featured location where esthetics are important.

As far as the root shoots go, IMO that's just par for the course with most crabapples.

I guess I will wait them out and see how they do this year and next spring. Luckily the trees were young and only had about 5 to 6 significant branches.

I have had several prime trees get this treatment............and they may have been set back a few years, but we also deer proofed them when nothing much was left but stubs. LOL. They're fine now and I expect shall turn out to be decent trees.

Crabs do sucker. Remove a bunch of top growth and they sucker more. Grafters leave some growth from the rootstock on for a bit occasionally to keep a tree alive while the graft takes.

I question if you should aggressively prune the suckers so the tree is forced to grow from the buds and dormant buds of the trunk or if you should leave any number of them growing to "keep the juices flowing" so to speak.

I do not have an answer.

In the nursery we "whip up" or cut off all the branches on crabapples and then top the whips at about 5' high in March when they are dormant as a matter of practice. By Fall they are nice looking trees.