A lot of people had sky high expectations for the GOP in the Midwest because we thought Trump was going to go full European big government cultural conservative. The libertarians held their ground much better than expected circa 2017, meaning that Republicans also held their ground better than expected in the South/West but actually lost some ground in the North.
My guess is that some states that either party made a run for will become part of the base while others will snap back. Just like how Democrats made a run for Colorado, New Mexico, Nevada, Virginia, and Florida, some of them are now fairly blue and others are becoming more conservative. For Republicans, they looked for the Great Lakes, and to a smaller extent, the Northeast. Republicans definitely snagged Ohio, Iowa, and perhaps even Wisconsin... but it looks like Michigan and Pennsylvania are snapping back.
I wouldn't make assumptions about Pennsylvania. It has a lot of Dems who went really far out of their way to appeal to working class indies and barely won. Also, the current Dem president was born there which almost certainly helped. IMO it could be on its last leg for Dems and pretty gone once Biden leaves office.
Recent lackluster performances and losses by Dems in Pennsylvania, as I've documented elsewhere, were the product of suburban #realigners not swinging Dem enough to recoup the collapse in the outer "WWC" areas. This internal movement has been going on in Pennsylvania for ages: compare the 1992 and 1996 elections, which had a nearly identical topline margin but reams of internal Dem movement from west to east and "the regions" to larger metros. Growth and diversification are centered on the areas trending towards the Dems, as is often the case, while much of the rest of the state is shrinking. I think it'll stay competitive for quite a while going forward, especially if more Dems can thread the needle between appealing to both of these sides as Fetterman is so skillfully doing right now.
Nothing exemplifies this and top-of-the-ballot-down trends better than Joe Torsella winning in 2016 and losing in 2020.