I would say that:

IF Microsoft has really thought through this new strategy, and mapped its product release timeline out with enough care and analysis so that it will stick with and expand upon Surface (and its new vibe/product range in general), and hasn't just rushed into a new look and is will flail about and switch to something new in two years - if Microsoft really is committed and focussed - and

IF Microsoft can match the confidence and self-assurance with which Apple releases and iterates its core products and

IF Microsoft can effectively communicate and deliver upon its vision of technology and

IF Microsoft can genuinely make people feel excited and good about themselves when they use their products and

IF Microsoft can attract a developer/user community which feels as comfortable and at home as Apple's -

then Microsoft could be back in business.

It's a big ask but it's possible I think.