The EU has been falling apart for a while know, But it really became a obvious with e refugee crisis and the rise of right-wing parties in almost all member states in the last 6 years. Major states like Italy, UK, Poland, Hungary, And Austria all have seen their populations vote left wing coalitions out of power in favor of center-right and right-wing parties. Dividing the traditionally left controlled EU between mostly West and East. Then Brexit Showed that if the people willed it a member state could leave the EU. Now with Poland and Hungary under attack and threatened with sanction from the EU tensions are higher then ever.
I see Poland and Hungary after being constantly attacked over not accepting refugee/migrant quotas from the EU the Visegrad Group (Poland, Hungary, Czechia, And Slovakia) would all vote to leave around the same time. As a consequence of this Italy and Austria left behind by their allies would feel outnumbered and oppressed by the other left-wing member states and vote to leave. Later I see many other Eastern European members such as Romania, Bulgaria, Slovenia, And the Baltic States leaving. The reason being the benefits of staying being significantly reduced being cut off from from Western members causing massive cuts in funding and also Visegrad and Russian Influence encouraging leaving. Lastly I see the EU losing significant power crackdown on all remaining member states making smaller and weaker states like Portugal, Denmark, Greece, And possibly others to leave or attempt to leave. The EU after all this could either completely collapse or be limited to a few states basically controlled by Germany and France. While the Visegrad Group could take the EU's role in former member states mostly in Eastern Europe only being a economic pact or maybe a military defensive pact if NATO dissolves too.
After all those events NATO would lose several member states. Assuming Donald Trump is reelected the United States would probably Allie with Poland and Italy. This would cause NATO members including Germany, France, Sweden, Turkey, And the remaining EU members to leave accept maybe Spain. This would cause NATO to be more focused on enforcing rules like each member state to send 2% of its GDP on defense unless it absolutely can't. Also It would focus on defending member states from outside forces like Russia, Turkey, And the remaining EU.
Overall I see the Eu basically collapsing into a Western European Alliance dominated by Germany and France. NATO would be weakened, But more united on ideology, Vision, And objectives.