I don't think this tells us much. The present distribution of supporters is rather unique in how strongly it correlates with population density, which means that Dems are going to have a major structural handicap in Senate. I don't think there was ever anything similar historically. And it won't change unless and until the coalitions change, which, sure, will happen eventually - but then it'll be a completely different party under the same brand, so why would Republicans today care about that new party's difficulties?
in American politics, 18 months definitely counts as an "anytime soon".
In the 2026 senate election, the Dems could absolutely flip Maine, North Carolina, and two others; maybe Alaska and Ohio.
If Elon Musk makes good on his threat to try to take out sitting GOP senators, that splitting of the vote could mean the Dems pick up a few more as well.
Because both parties are scared eventually the other party will be back in the majority.