I think your plan of upgrading wheels to carry over to your next, purpose-built bike is a good strategy. I would try to minimize the extra cost of touching much else on your current bike..... as long as you can ride comfortably for long distances and you're happy with the gearing, etc. then don't sweat the rest of it.

I've also been really lucky to find both 700c and 650b hand-built dynamo wheelsets off my local craigslist for dirt cheap. Hoping you can be as lucky as I. 700c is easier to find than 650b around my parts. After getting a dynamo wheel, I splurged on an Edelux II and a B&M tail light, which I carried over.

If you can save on the wheelset, (e.g. spend $300 vs. $800), you can immediately put that money towards a rando frameset or a more appropriate project.