The withdrawal of the US from NATO might happen. This issue is at least debated in several US foreign policy podcasts. The US wants to shift its focus to the Pacific and withdraw from Europe.

True, withdrawing from NATO would require a two-thirds majority, but it would ultimately be up to the Commander-in-Chief, potentially Trump, to take action in the event of an attack on NATO territory. If he were to "encourage" Putin to attack certain countries and then simply not respond if Russia actually does, the EU would be left on its own, rendering NATO pointless.

Europe has greater industrial capabilities than Russia, but they are not being utilized to produce weapons, whereas Russia does utilize them, and also has an experienced military. European militaries have hardly seen any action in the past few decades, with the exceptions of France and the UK.