Old people need care constantly which will increase Poland's retirement home
I don't think so. Unemplyment is not a problem in modern Poland, a lack of workforce may be. People are more skilled, more qualified and more ambitious, even now most of low paid jobs are being done by Ukrainians. Not to mention in the future.
Native countries will have to take care of their aging workforce, which they used to produce value for their economies. Poland will not a be a haven to some old farts from Germany and Western Europe :-)