Having now completed one Unity game using Playmaker on my own, I have the following advice for developers in a similar situation:

1. Aim for small, simple games you can do yourself, and play to your existing strengths. I thought Unknown Orbit would be so simple I'd get it done in a few months. If I'd cloned Tiny Wings, and not gone for a rather difficult 3D planetoid/moon setup, then perhaps that would have worked. However, you should think about things that will take up a lot of your time -- namely characters and animation. Even simple 3D modeling will take you some time if you don't come from an art background. My first job was a 3D modeler, but it still took me time to get back up to speed on Blender.
2. Use a simple art style with reusable assets and gameplay loops (see this Lost Garden post on loops vs. arcs.) A story-based game with loads of content and 20 unique levels will take a long time just to create the assets, whereas something like Super Hexagon is the perfect example of a game with little in the way of art assets.
3. Use Creative Commons assets, especially for sound and music. Freesound.org is the best! Make sure you don't just note that there is a CC logo attached -- read the license and make it sure allows commercial use. I leave the file names intact so that I can go back and make sure everyone is credited properly.
4. Try to find an advisor of some sort. This can be anything from the people on the Unity and Playmaker forums, to the unity chat channel, or the numerous playmaker/unity3d tutorials. I highly suggest looking at WellPlayedGames tutorials for learning Playmaker. Without a helping hand or two, I would have spent a lot more time banging my head against the wall.
5. You will probably need at least one or two bits of code (shock horror!) I had Saxon from Binary Space on my side to help with the high score system. As Playmaker progresses, chances are we will need less and less code, but for now I think a good number of games will need at least a little. One recent addition has been an array maker that Jean Fabre has written, which I could have potentially used for the high score system.

So yes, coders might still be required for some games, but proving that you can make/release a whole game on your own will prove to yourself, potential partners, funders, Kickstarter backers, etc. that you have a work ethic and can get things done.

As a further note, strangely enough I've found that using Playmaker has actually solidified my understanding of things like object oriented design and other programming/design concepts. So I think it can be helpful in learning these concepts as well!

If you're a creative or just really want to bang out a prototype with great speed, I highly recommend you try out this combo of Unity/Playmaker.

Here's the end result of a years worth of work (part time) on Unknown Orbit, by one guy with no programming experience, some 3D skills, and some game design background, made using the iOS version of Unity and Playmaker.

Unknown Orbit was developed by Jay Weston at Exbleative and is now on the App Store for iPhone and iPad. Unknown Orbit lets you float, jump and fly around a surreal, 3D planetary system as a comet. Find out more here.