That probably means that by fall availability Microsoft means early fall, which is good news for current and future owners of WP7 handsets. We wold bet on future owners who get the handsets around that time, however - current owners might have to wait more, as usually happens with these updates, but let's not put the cart before the horse.
Microsoft itself is not shy with sales forecast for Windows Phone. At the WPC 2011 partner event COO Kevin Turner said they expect about 100 million handsets with Microsoft's mobile OS to be sold each year in the future. Nokia sold 108.5 million handsets in Q1, so almost its whole lineup has to be Windows Phones for that number to be achieved, and we still don't know how the market will accept the brand repositioning.
There are other WP7 manufacturers, of course, and new ones are coming onboard, so we'll check back at the end of 2012. At about $15 per license, such a number would mean Microsoft will recoup its roughly billion dollar initial investment in development and promotion of Windows Phone 7 for a year.
Meanwhile, Nokia plans to spend about $130 million in the UK alone to promote the transition, while Microsoft will build 75 additional retail stores of its own. "We have to do some very strategic things to get our mobile phone volume up", said Kevin Turner, and we are sure Microsoft, Nokia and the other Windows Phone partners are perfectly capable of becoming the third ecosystem, injecting some healthy dose of competition.
source: WPCentral & WMPU