Regarding Kurzawa, he was highly rated as a youngster, no idea how he's doing now but AFAIK, he's very good going forward.
Also he's a United fan :
"The club of my dreams? Manchester United. One of my goals is to play for them one day."
There were rumors that PSG were ready to sell him for 25 mill Euros, which is actually a great price for a LB who's just 25 and has experience at the highest levels.
IMO we should buy him for that money. Looking at our LB options, Shaw is a goner and Young is 32/33
Even if we bring in a new LB next year, buying Kurzawa this year would give us a good cover and next year when we buy a new LB, he can be second choice as I expect Young to have declined a bit by then and Shaw to be sold or to have left on free
But if PSG sell Kurzawa ,they will most probably sign Sandro, so that's our #1 LB target gone