FYI there are still LGA1551 and AM4-based boards with PCI slots available, at least in mATX and ATX form factors. So you could potentially replace it with a modern board if you wanted.

https://pcpartpicker.com/products/motherboard/#xcx=0&d=1,6&s...

(although apparently not in mini-ITX, but there are still a few Atom boards with ITX and PCI non-E available)

https://pcpartpicker.com/products/motherboard/#xcx=0&d=1,6&s...