My expectation at this early stage is a net of 0 or -1 - Dems flip NV and AZ but suffer their own losses.
Though DKE posted rumblings that Wagner might not run... in which case, good news for Air Claire
Wagner is a good fit for the St. Louis suburbs that Blunt cratered in (he only won St. Charles County by 7! That's unheard of for an incumbent R), but she's persona non-grata among the Trumpists after her endorsement flip. I have my doubts she'd get a clear primary, and would probably lose one to a decently funded opponent.
I think the next Democratic statewide victory in Missouri will come from suburbs not rural areas. I would not be shocked if St Charles County voted for a Dem (even if barely) in the next statewide Democratic victory. Ste Genevieve is probably the only rural county that would vote for a Democrat in a statewide victory. But one has got to wonder if it is easier to flip rural voters in the lead belt or exurban voters in St Charles. You could really argue the former might be true because as you look at maps and election swings rural voters tend to swing a lot more.
Anyway, Wagner should run. She would be favored to over take McCaskill and I would be interested to see if Democrats could compete in an open MO-02 without a Democrat in the White House. Even this year, it was quite a split ticket district. Plus in 2010/2014 and 2016 there was always a State Senate seat that Democrats won within the district and they were all seen as sort of consolation prizes.
Also if Trump implodes the fact that Wagner unendorsed Trump, even if briefly, could help her cause to be honest. Of course it is one of those issues that could very much go either way for her.
As for the topic of this thread:
I would recommend that Democrats not get too obsessed with taking over the Senate. Very unlikely to happen. Chances are better in the House and Governorships. After eight years of Obama, Democrats are in an awful position in state governments. Try to win House Seats back, even potentially take the US House. Try to win back some legislative seats, win back some governorships, win County Offices to create a bench for future statewide races.
A county Treasurer elected in a medium size GOP-leaning county could be a statewide Treasurer/CFO/Auditor candidate in the future for Democrats. A new State Senator from a light-gop leaning suburb who is an attorney could be a future state Attorney General candidate.
As far as Utah Senate 2018, I hope it is interesting. Utah needs some exciting race. I do wonder if Matheson may change his mind to try to get in. But I think his current career could well hurt him. He does not seem to mesh well with Democratic House Members but perhaps he can get along better with Democratic Senators.