Totally playing devil's advocate here... but Symbian was selling well but not at the same clip as they were before since attention was shifting towards Android and iPhone faster than the updates to Symbian were coming.

The burning platform was indeed a fiasco. Something that hastened Nokia's downfall. Blame the Osbourne Effect for that - announce something is coming to replace your just released product. A product that didn't come out for almost a year after that statement.

Anyway, Symbian was on a downfall. Fast in all areas but Asia and most of Europe. It was a non-factor in Japan (Nokia has been a non-player there for ages) and mostly it was relegated to lower-priced, lower tiered phones than most Android and iPhone purchases. With Android going down in price and trending that way, Symbian was bound to lose even more - which it did.

The burning platform was, for all intents and purposes, more about the inner-issues within Nokia and their choice of "religion" of where they put the majority of their money into than it was about Symbian going away, imho. Especially when he needed to make everybody into one religion, Microsoft... that ledger leaked to accomplish just that.

And it worked. No more MeeGo. No more Harmattan. Less Symbian investments. And two iterations - WP7 and WP8 - of Microsoft and a stock price to reflect that dedication.