I think one of the problems in being a small, early stage Mac developer is that a lot of us have to resort to doing things in our "free" time, while still working another job to pay the bills. There are some things that could help matters, but it's still VERY tough to generate enough revenue to do Mac development full time (at least from my experience).
What could help? Well Apple tapping into a bit of their $4 billion to seed "really great ideas" might help. Think about it, distributing $10 million a year probably wouldn't make a noticable dent in Apple's cash, but it could allow a bunch of Mac developers to break their chains and do their Mac software full time.
Another thing Apple could certainly do to help small developers is leverage the OS X downloads site. Currently, the "New This Week" section often goes for weeks without an update, and lately the software they have been showcasing has not necessarily been of the highest quality. Even so, getting a listing there can lead to THOUSANDS of downloads. If they could make it a more dynamic site, and add an ecommerce piece, it might make it easier for users to find, download and but the software of small developers.
It's a big leap of faith to say that you are only going to do Mac OS X development, especially when the Windows market is so much larger. Anything that could make the decision easier would certainly help.