Refurbished Nikon D750 DSLR cameras are currently listed for sale on eBay for $1,229.99 (regular price: $1,796.95). This is a new low price – the last price for refurbished D750 cameras was $1,399.
Refurbished cameras come with a with 90-day Nikon USA warranty.
I have no information about a potential D750 replacement being released anytime soon.