I don't know is the answer - if all the root material 'fell' off, leaving just a stump, probably not,but if it still has roots of some kind to go beneath the soil, it may recover. Keep it well watered though.

This is one of those cases of "wait and see". Cross your fingers and hope!

If in doubt - drench with vine weevil killer ASAP. First year in several that I have noticed such an infestation affecting pots and plants in the border.

I would also prune it severely, to keep the bush from drying out before it can grow new roots. My experience is that roses are surprisingly tolerant of snafus like this.

Best way to tell if you have vine weevil is to tip it out of the pot onto a sheet. Vine weevil grubs are white curled grubs about a cm long with a brownish head ... easy to spot in the compost. The adult beetle is a black beetle so if you see this in your beds and pots in autumn, squish it! Check google images for identification. Apply a vine weevil killer drench to all pots and beds - laborious but worth it, especially in terms of replacement costs.