Doom is trying to use The Ten Rings for multiversal travel
I'm guessing Doom will use the incursion as a smokescreen to hide his real intentions from The F4. He doesn't cause it, but is familiar with them, and has an understanding of traversal. He may even have a few methods on his radar. The ten rings, America Chavez, Reed Richards ship. My guess is the ship still needs to find a tear to go through. Since America Chavez can easily hop around, he convinces Reed to come to 616. He then tries to take the rings from Shang Chi. I'm guessing he does but the end, or he takes Americas powers