"It depends" is always the right answer, and while I have no experience personally with olive, I would think that there is likely to be some viability in some of those stumps. Olives, like many of the ancient cultivated plants, became cultivated due to its ability to propagate easily from cuttings. I would imagine that some of those early plants were also propagated from trunks and they did not always have optimal care. I would certainly try to grow some of them out, and as suggested above, I would attempt this in multiple ways. Good luck. Please follow through with this and let us know your results. Many people here would love to have the opportunity that has presented itself to you.