What will Washington State look like in the future (geologically)?

Question

Will pieces of washington separate?

What will happen to the shape of washington in the future based on scietific facts?

What will it look like in 100 years, as well?

Answer 1

I would only conclude that Washington State will look different - pieces might separate over geologic time, particularly if the Yellowstone supervolcano cuts loose again.  

You can reasonably extrapolate the changes over the last 100 years and use that as a forecast tool for the future - more urbanization, Mt St Helens or Mt Rainier might erupt again, erosion would remove some material, but I don't suspect there will be substantial changes in the state for the next 100 years - that is a very short time geologically speaking...