I live near Montreal - we have cold winters. I have a magnolia tree planted 6 years ago which flowers with yellow flowers. It was planted to celebrate the birth of my first grand daughter. This year was very wet and although we had some flowers on the tree they did not open fully - they withered and died.The leaves didn't come out either, However we got 4 shoots from the roots which have made huge leaves and have shot up to great height. What do we do? Cut down the tree (it seems dead). Do we replant the shoots separately or do we leave the tree to its own resources? I love the tree and would hate to see it go from my garden.
Your Magnolia very well was a grafted variety. The shoots are likely growing from the root stock, and it will be different then the tree you had.
Whether it blooms or not, I can't answer.
I would replace the tree with another pretty specimen that would celebrate your granddaughter.