I believe if Nokia continued to invest, MeeGo would have even gotten better and they would have survived (note I worked at Nokia's subsidiary HERE maps at the time and saw early version of MeeGo. Also the hardware of the N9 was beautiful. It would have been a hit and in fact outsold the Lumia in the few countries it was delivered before they axed it).
I'm sure some of the gushing praise it got was because it was a last hurrah, but if Nokia had actually supported it, I'm sure it would have sold tens of millions of units. Nokia sold ~100 million smart phones in 2010 and ~ 77 million smart phones in 2011 [1], Apple sold ~ 72 million iPhones in 2011 [2]. While the trend was going the wrong way, tens of millions of mobile users would be hard to ignore.
[1] https://www.nokia.com/system/files/files/request-nokia-in-20... (page 8)
[2] https://gadgetadvisor.com/apple/the-iphone-decades-iphone-sa...
WhatsApp was on Windows Phone though.
Instagram was not on Windows Phone, which hurt it, but there is no indication it would have come to MeeGo either.
Even given that the Android team actually did understand what they needed to do to achieve that. Nobody else in the industry did. They thought that if you just ported an OS the job was done. That’s barely even the start.