Mr. Dragon ,
Do you really think all elections will exactly match 2016 forever? No midterm recently has matched the previous presidential election well so there is no reason to think 2018 will be just like 2016.
Sure we are polarized but candidates, level of office, campaigns, circumstances and climate do matter.
No, I don't. But outside of someone who is extremely popular (which Stabenow isn't), no senate democrat in a state that a republican presidential candidate just carried starts out completely safe, and no senate republican in a state that a democratic presidential candidate just carried is completely safe. (And that's what a Safe category should mean - completely safe)