Suppose you plan to take some pictures with a camera. One possibility is to conceive your idea, with all the visual details, all the photographic properties, clear in your mind. Then you can go and scour the earth for a camera that will accomplish that, ideally easily. The other end of this spectrum is to find a camera, perhaps one already in your closet, or if you prefer at some store. Go forth and practice with this camera, and see what can be done with it. Finally, conceive and shoot some pictures that the camera is capable of producing.
In the first case, the cart is well in front of the horse. In the second, the two are the right way 'round, but arguably the cart is rather too far back.
The point is that gear informs vision, and it should. This is, really, the entire thrust of my approach to photography and to teaching photography. Go shoot with the camera you have (don't "practice" endlessly, just go try it out). Look at the results, look at what the pictures look like. Then, use that as you struggle with your muse and try to find something to say. If you simply let it happen organically, the pictures you conceive will fit neatly into the pictures your camera can make. If it just won't happen, well, then maybe a gear change is in order, sure.
You can make beautiful pictures with anything. You can make interesting pictures with anything. You cannot make every possible interesting picture with every camera, but you can make some interesting pictures with any camera. Frankly, it's difficult enough to conceive an interesting photograph without having to contend with some infinite universe of possibility. You ought to welcome some limitations.
Sally Mann shoots this wet plate stuff, which has absurdly long exposure times, and often has all manner of weird artifacts. This has, clearly, shaped her vision of certain things. She's fully capable of shooting sharp, artifact-free photographs on film. She's done a lot of that. But she lets the wet plate methods shape her vision, and she flows with those visual ideas to produce some truly wonderful, amazing, things. So you're shooting wet plate, and the exposure is 6 minutes long. What can you shoot with that?
You've just got to work with what you've got, to develop an idea, or ideas, that work with what you've got.
Of course vision will ultimately shape your gear choices as well, but it should happen in an evolutionary and organic way. If you insist on buying a new system, with completely new visual properties, then in a way you're throwing out all that you knew about the one you're "upgrading" from. There will be similarities as well, of course, but if you insist on revolution then by definition the changes are quite radical and you are, to the degree that the changes are radical, starting out anew.
While I am not a commercial photographer, I submit that this isn't a bad approach for commercial work either. There are certain restrictions, of course. You have to be able to make pictures that are usable by your target market (perhaps that means sharp enough for print, or in color, or whatever) and you have to be able to make them in a way that suits your clients (a single-shot pinhole camera is unlikely to work for weddings). But if you have a vision that's sufficiently commercial to sell, then by definition you can sell it. If that vision is shaped in part by your equipment, so what? If you "upgrade" in a revolutionary way you're just going to have to start over, selling the new vision. "Yeah, I'm shooting large format now, and the pictures look totally different from the ones in my portfolio, but they're ever so sharp..."
The cart and the horse are fastened together. Each pulls on the other, and that is as it should be. But if the horse is not in front, you're not going to get anywhere.
If you don't let the gear shape the vision, to some degree, you're going to be locked in an eternal quest for the right gear. You're never going to find it, and if I catch you at it, I'm going to yell at you.