[Build Complete] drawbacks of upgrading GPU first then CPU/mobo?

Hi, This is my current rig http://pcpartpicker.com/p/vK2JjX (about 4 or 5 years old now)

I was thinking after this summer id pick up a 970, then once i got the money id replace the motherboard and the cpu, My question is, am I wasting money upgrading the GPU first then getting the CPU+mobo?

I think a 970 would breath some new life into this machine until i have enough for lets say a i3 4170 and a mobo for it. Am I wasting money doing this? thanks for your help.