The I5-2500k currently isn't a Bottleneck to the GTX 970 when it comes to gaming. While certain recent games might recommend something more recent, and Overclocked I5-2500k can usually keep up with those specs. Given the current situation, I would strongly suggest that you wait and get an LGA1151 motherboard with a skylake chip and DDR4 ram when you're ready instead of rushing it and getting an older processor.
However, if you can get a really good deal on an I5-4690k because of a sale or something, it's definitely not going to be outdated tomorrow, so it is a viable option.