Open Source could be an advantage for them if they change their license to the AGPLv3. With an AGPLv3 license, any competitors would be required to make their modifications available for download. But as the copyright holder, the OP would not have to release any source he didn't want to, giving him the flexibility to run private, closed source extensions/enhancements if he chooses.
Keeping in mind that he can't make use of any competitors' (or even friendly open source contributors') patches because they will be licensed under the AGPLv3 and not under his copyright.
I guess they could sign the copyright over to him, but I don't see another way around that. (IANAL)
You only have to sign it over if you want it in the official distribution, which I suppose most normal contributors do.
But if someone (competitor or not) forks and adds SuperAwesomeFeature (without signing the copyright over), pkrumins can't pull that into his and license it commercially. It'd have to only exist in his AGPLv3 version, which sounds like hell.
No, he can't pull their changes into his commercial version, and he'd probably want to avoid pulling their changes into his AGPL version. But, the hypothetical forkers would also have to re-apply their patches to pkrumins version each time he comes out with an update, assuming they want to incorporate his changes. It's close to a level playing field, with what I'd say is a slight advantage for pkrumins. As opposed to the situation he's in with any other Open Source license.
The only danger for pkrumins is if the "forker" is able to make his new fork the more popular, more advanced fork. That doesn't happen very often, and really, when it comes down to it it's just a case of being out-competed, which is a danger every business faces.
IMHO, it comes down to whether pkrumins is going to gain more (in mindshare, in community contributions, etc.) by going open source, vs entirely closed source. If he's going open source, AGPLv3 lets him minimize the leverage his source releases would give to a direct competitor, with no likely reduction in his upsides (i.e., the previously mentioned increase in mindshare, the community contributions, etc).
That's of course hypothesizing that there are upsides for him in going Open Source. Clearly he seems to think there are.
Any GPL-like license, yes. But people like to bring up the AGPL because it means "Muhahaha, if they ever run it as a service over the net it means they have to share their source!" as if it has any benefit to their commercial product.
This is an interesting thought exercise. I'm going to postulate that there is a benefit of the AGPL. Lets take a look at a company like JBoss, who may have benefited from the AGPL opposed to the LGPL they use.
A company who wanted to use their products for commercial use must provide a link somewhere on their page to the source, and share any mods. I think this is a big incentive to buy a commerical license from them, as it may look a little less than professional.
Assuming they don't though, and they publish their changes, there is still incentive for them to sign over the copywrite. If they want any backwards compatibility for updates and bug fixes (very important for a runtime platform), they need to. Its that or port everything back over.
