A hypothetical sequence of events:

Google bids for NOK (current market cap: $24 billion) - not a huge bid, but enough of a premium to make Nokia’s long-suffering shareholders take notice

Microsoft must counter-bid, or face complete devastation in the mobile OS market

Microsoft and Google bid, and Microsoft puts up enough money to win, as it must (see point above)

Microsoft becomes a vertically-integrated manufacturer of smartphones, Apple-style, and ventures into unfamiliar territory by selling direct instead of through the channel

Google spins off or writes off the useless stump of Motorola (ie the hardware side and everything else bar the patents)

Google has now usurped Microsoft’s place as the OEM-neutral, massmarket provider of OS software