depends what kind of impact win8 has on the tablet market. seems like android is kind of weak here compared to iOS. If Win8 gets a big enough chunk of that and if WP8 is more or less compatible with win8 on an app level win8 powered tablets could pull windows phones along enough to get reasonable market share. Microsoft certainly has the reasources and cash to at least try that. As far as RIM is concerned, I see their future as kind of bleak...
Leveraging tablets to increase WP sales is the best path for MS to take but they are playing a dangerous game.
Windows 8 on the desktop will be a serious adjustment for consumers and very early reviews seem to indicate that. The perception of Windows 8 on the desktop could adversely affect WOA.
Sure it's a gamble, and a risky one for that. But continuing business as usual is IMO even riskier. Possible that Win8 could face the same fate on desktops like Vista did. How that wuld effect customer perception of Win8 on tablets, well good question.
the main benefit I see in Win8-tablets is that you finally get a real computer for the price of a real computer and not an oversized smartphone you can't use to make phone calls for the price oy a computer. But that's just my opinion.