Gold Rush in rebuilding or more precisely modernization of the country is not going to happen that is just the bullshit they like to spin for the credulous, same goes for EU membership, not happening in less than a couple of decades.
Anyone who gets work and builds a life abroad in a more affluent country will be hard-pressed to move again to lesser prospects.
Like said brain drain will continue for decades, aging Europe needs qualified workers nurses, doctors, teachers........... and we rather take Ukrainians than Arabs or Africans. West has drained eastern Europe in a similar way, member states in the east are depopulating at extreme rates.
People move to better paying jobs in western europe , freedom of movement inside EU accelerated the trends for eastern europe
As for Financing Ukraine , if you read carefully, much of the financing of Ukraine is in form of loans , most of that is not going be just written off.
Black Rock, JP Morgan and similar wallstreet locusts Zelensky just signed on will strip mine and privatize anything of any value and IMF will do its own shock therapy. (austerity politics is IMF standard MO)
* UK paid last of the US WW2 loans in 2006.
Most countries have just spent shit loads of money on faux rona and now on financing war in Ukraine while subsidizing the eonomy and domestic energy costs and the dumb fucking green transition BS is only gaining steam., Of the charts, money printing caused runaway inflation so they might not want to repeat it on a similar scale . I just dont see anyone willing to throw money into Ukraine once it drops off Tv screens. (have you seen any substantial help coming to Turkey that lost more civilians than Ukraine in the earthquake, practically peanuts in line with nonexistent MSM coverage )
Only ones that would be game are Chinese , but they tend to bring everything from the workforce to materials to their build sites around the globe. And that is actually been the case in the aforementioned wars, the west packed up , Chinese moved in.