Development cars tend to be crushed as they attract too much VAT given the cars are usually worth 4-5 times the 'value' of a production car and also the OEM would have to pay VED on all years used too (they get it for free on development fleets). Note Demo/press cars are usually very very well built production cars and can be sold.
So yeah, dev cars get crushed eventually... We have two DBS's and an Evora that will be crushed