I guess it is. Cyanobacteria can survive in dormant spore-like thick-walled, nonmotile cells called akinetes, when environmental conditions are unfavourable.
However, I don't think it necessarily means they will inevitably make a return just because they were present before.
Very good question. I suspect the answer is - yes.
There are hundreds of species of 'BGA' (cyanobacteria) and some seem to survive drying better than others. When I recently investigated which species I had in one of my tanks, it turned out to be Oscillatoria.
Why not do a little experiment? Put some of your soil in a suitable container with tank water in a well-lit location and see if anything develops? It's probably worth adding a couple of fish food flakes to release organics, etc. into the water. Please let us know what happens.