I see nothing, so far, in Windows Phone 10 that is a game changer.
Well, so far we've seen nothing but screenshots. Even when the preview is released, it won't be what it WILL be later. The real game changing stuff is "write once, compile for anywhere" type of strategy, though.
Definitely not true about the dev tools. Visual Studio 2012+ is *far* superior to the iOS and Android tools.
It's all about marketshare.
Yes, you are absolutely correct here. The issue with VS 2012+ is that it currently doesn't create apps for iOS and Android, so this brings up 2 problems.
1. You have to use ONE IDE to create for iOS and Android, then use a DIFFERENT IDE to create for WP. As a retired developer, I always wanted to do everything in one IDE. Remembering functionality quirks across different IDEs just makes you less efficient with both.
2. The marketshare does not currently make it worthwhile to deal with the pains of using different IDEs, and having to do a complete port to another OS where most of the code has to be re-written.
Microsoft will be releasing a new version of Visual Studio most likely by Summer. Once released, this version will write and compile for iOS and Android, as well as Windows 10 Universal Apps. While this will help developers that don't want to use multiple IDEs, there still remains the issue of having to port and change a lot of code from iOS/Android to Windows 10.
Microsoft is working on a SDK for it that will allow writing once, and compiling to all three, which will make porting between platforms a cinch. That will attract developers like fleas to a dog. Once they start writing their iOS and Android apps, and discover how easy it is to press a button and make one for WP, Windows Tablets, Windows PCs, XBox One, Surface Hub, and HoloLens, a great number of develpers will begin to do so.
Don't expect Google to develop anything for us, though. They think WP will fail without their services, but in the end, Google is going to hurt themselves with this approach.
The developers who will take longer to convince are the ones that are being "silently strong-armed by Apple and/or Google", where I personally believe that Apple and/or Google may be convincing businesses and developers not to develop for WP recently, because they are afraid of Windows 10. How do they convince? "If you make an app for WP, we'll pull your app from our store, and you'll lose the biggest market share of customers." Is this going on? I don't know, but I think with the way Chase has scolded employees for wanting to talk to customers about why the app was removed/cancelled, because it violated a non-disclosure agreement. I'll bet that agreement was with Google or Apple, because both are unscrupulous enough to try something like that, as illegal as it is. Do illegal things go on in business? If you believe it doesn't, then you're just naive. I'm not saying this happened, I'm just saying that in at least one parallel universe, it could have.