If they gave up entirely on their foreign policy objectives a more likely scenario than tanks would be the Russian State ending up a fragmented, powerless mess.
I don't imagine a US led NATO coalition immediately rolling tanks into Moscow if all 5 countries flip to NATO, but stirring up a separatist movement on the borders of Belarus or Ukraine and then "helping" out? Definitely.
I don't for one second believe that the US will instantly grind to a halt after creeping up on the Russian border for 70 years.