Will Dragons continue to spawn (regular dragons, not named dragons. Ex: blood dragon.) after the main quest is completed and Alduin is defeated?

Yes indeed. Dragons are just like all other animals in creatures in the sense that they spawn randomly and go about their business until they run into you...

but alduin is resurrecting them. how will they continue to spawn if he is dead? i think they will stop spawning

it is already confirmed a long time ago that they will continue to be there. im sure it will be explained in the story.