Poland can rely on the extensive expatriate community to help recover.
But after living in a different country for 20 years- in which time many expatriates would likely have their own families to care for, would you really want to move back to your war ravaged homeland?
I think that Poland could become a successful country in the future with preferential economic agreements with the USA, UK, Canada etc. It could market itself as the 'gateway to Eastern Europe', acting as a major hub for investment, transport and trade- Italy, the Netherlands and Scandinavia aren't going to want to deal with Germany, France, Austria, Croatia or whats left of Russia for many years. Poland is now a blank slate, and unlike its neighbors, the international community will actually want to do business with it.
Depending on how much mess remains, Poland may be the only viable tourist destination in Eastern / Central Europe for many years as well.
An excellent conclusion to a superb timeline, Calbear.