"The most likely final chap­ter in its sto­ried his­tory sees Microsoft buy­ing up Nokia's siz­able patent port­fo­lio, its in-house design and engi­neer­ing exper­tise and -- per­haps -- the brand rights," Jonathan Murray, now a Warner Music Group executive, wrote in his blog.

In his post, Murray says he is certain that Microsoft will become a man­u­fac­turer of a full range of Win­dows 8 based smart­phones.

"When Microsoft launches a 'Sur­face Phone' it is quite sim­ply game over for Nokia."

According to Jonathan Murray, Nokia’s strate­gic options are shrink­ing rapidly.

"It’s my view that when Microsoft enters the phone busi­ness with its own devices Nokia will have run out of time as an inde­pen­dent com­pany," he blogged.

Murray also speculates that Stephen Elop will eventually be back on Microsoft's payroll.

"Per­haps Nokia’s CEO Stephen Elop will even rejoin the Microsoft lead­er­ship team to run the phone business. Alternatives to this out­come seem to be very few and far between."

Analysts: Monday do or die for Nokia

The launch of Windows Phone 8 on Monday follows Friday’s release of Windows 8 for PCs and tablets.

Analysts are calling this a make-or-break moment for Nokia.

"Nokia is placing a huge bet on Microsoft and if the gamble doesn't pay off, the losses can be high," said Neil Mawston from Strategy Analytics. "It's putting all its eggs in one basket and that's quite a high-risk strategy."

Mawston is giving Nokia until April to prove it’s still in the race.

Analysts estimate Nokia's current global smartphone market share to be some 4 percent, down from 14 percent a year ago.

On Friday, research firm IDC said that in the July-to-September period, Nokia slid for the first time off the list of the top five smartphone makers in the world. It's still the second-largest maker of phones overall, but sales of non-smartphones are shrinking across the industry.