Cardin might retire, though I kinda doubt it. If he retired, it might have a downballot effect, where a subpar Democratic nominee for senate could give Hogan an easier time running for reelection, or possibly even cause an upset win for Republicans in the senate, though it's unlikely. Maryland is not known for a lot of split-ticketing.
Other than Cardin, I can see Carper possibly retiring. I'm convinced Heitkamp will eventually feel good enough about the national environment to run for reelection.
There is absolutely zero chance that Maryland sends a Republican to the Senate in a Trump midterm.
