I agree with your 2c. If Apple rebrands the Mini into the Macintosh and bolsters the internals a bit, great. The colors angle, sure, I can see that too. Given the red Mac pro and various colored iPhones, iPads, colorful Macs make sense.
Tomorrow (!) does seem to point in being a Mac event and should the Mini be replaced by the Macintosh (or xMac), I'm okay with that.
I don't see the Mini being replaced because of its price point but the addition of a Macintosh desktop with desktop components in the Pro cases in a distinguishing color would be a welcome addition to fill the gap.