I don't think we should bring back Prussia. East Prussia has always been seen (at least in eastern Europe) as a symbol of German expansionism. Plus, Germany refuses to remove territory claims, and Prussia would likely face economic issues.
For all my Hetalia fans out there, Aph_Latvia, TinyTots101, and I are starting #bringbackPrussia, since the country no longer exists. If you want to help, re post this on your page.