If it's an early 15 reg car I'd say £16k is about right as a trade in at honda. Pretty sure when i bought mine i was offered £16k as the GFV if i took it PCP after 3 years. Anyone not looking to lose a lot of money should not be buying a new honda! loads of performance cars that can be bought used and run for a year or two with very little financial loss, a fair few you can expect to make money on if you choose sensibly. A friend of mine has lost £14k on his M4 since august last year! makes the type r depreciation seem a lot lighter. Just a case of someone not going in with their eyes open.
I'm surprised at the number of people jumping ship from the fk2 to an 8 in all honesty (yes i know it's a step up, as i've driven two) The fk8 is going to have a much longer production run than the fk2, best to enjoy the fk2 smash some miles on it, enjoy them, get your money's worth( by this i mean a good 20 to 30k miles,) Then step into the mid life face lift fk8s that will no doubt come out perhaps a limited edition or hopefully one with some more power too with a long production run i'd say more power is inevitable. interesting to see how the fk8s depreciate as they are making a lot of them in comparison to the fk2s. As soon as the fk8 was announced it was clear the fk2s would take a proper hammering in terms of value.