The thing is, Universal apps are new... A project like this will take MONTHS if not years to find out of it really is successful. No one has a clue if they will or wont work.
Windows Phone is the bigger question here. So, devs now wont make an app for Windows Phone....maybe they love their iPhone, or Android device, or they just think that it's not going anywhere (with Microsoft saying they are not chasing the market, I see their point) So they start making an app for Windows 10 PC (10 million people have it, good amount of people, great exposure), If they don't like Windows Phone for some reason, why would they even make an app for Windows Phone ? Why bother ?
Will this SAVE Windows Phone ? Who knows but, we should all hope it does. Microsoft is taking a back seat on Windows Phone now, NOT chasing the market, releasing only 3 devices a year but, no promotion and only for the fans/corporate users. This is a VERY bad thing. Microsoft has done this type of thing in the past.
I give it 2 years.. This is Microsoft's check time, If the Market place has not really grown (so we get 10 apps but, we lose 12 apps, it goes no place), and the market share is still sitting around 3-4%. Microsoft will put an end to Windows Phone.
I have been following Microsoft as a company from the Windows 3.0 days, I have been following news, podcasts and any other outlets, I have seen how Microsoft does business.
This could be the start of the end if things don't pick up....but, this is with out big money for advertisements and BUYING apps from Microsoft...
Trust me when I say it, Microsoft has done this type of thing before.....but, that was over a few million dollars....Windows Phone has cost Microsoft in the BILLIONS. Think about it..