I really wish people would stop talking about the future of Windows Phone as if it has saved the platform. I'm really excited for the future and I hope it does save the platform, but most people don't know anything about the future with Windows 10. They don't go on sites and forums like these. They see what is currently out. iPhone 6/6+, Note 4, and they know the Galaxy S6 is coming. They buy these phones on contract because most people do not know about buying a phone outright, nor do they want to spend $300+. So now there goes another customer for 2 years. There is essentially no flagship. In the US you have to be on Verizon to get the icon or the absolutely gigantic 1520 on AT&T. The 1520 is too large for what many people want so it's out and there's nothing else comparable. Verizon users can't have the 1520 they might want. A friend on T-Mobile wanted to switch back to Windows Phone now that his two years are up. His option is the 635? Get a crappier processor, no front facing camera, a worse screen, etc, etc? He's not going to downgrade to a Windows Phone. Another friend on T-Mobile has a 925. He has no upgrade path. His wife has an 8x. She likes to use snapchat and instagram. Well she might not understand what 6tag is, and there's no snapchat so her upgrade will be back to Android. Developing multi-platform apps may not be a lot more work, but to be able to develop something that is pretty similar between iOS and Android then have to make a bunch of new assets and designs to layout to fit the Windows Phone ecosystem is something that may turn a developer away especially when the userbase is undetermined.
I've mentioned in other threads that I've experienced the ridicule of owning a Windows Phone. I really like the 1520, but again it's gigantic and really my only option as far as a flagship currently goes. Microsoft needs to start with a flagship that improves upon the 1020s camera. That's the one thing people do favorably talk about when it comes with WP. Then they need to take that flagship and make sure it can come out for all carriers, so everyone can get it. That alone would be a good start in getting more users. People willing to try the platform are more likely to if they are getting awesome cameras and hardware and know that they're getting a phone that will be better than what they're currently using.