It depends on whether or not you can wait until at least October, probably close to November. It will be another 6-7 months likely before the Pixel 3 sees the light of day, so a fairly significant amount of time. If you think the Nexus will last you another solid half year, you can wait. Otherwise, grab a Pixel 2. Phones tend to not be vastly different year over year, so in my opinion it's worth upgrading to a Pixel 2 now. It's a big enough improvement over the 6P in my opinion. I usually upgrade my phone every other iteration as I find 2 years to be enough with one particular hand set. Usually over a 2 year span there's enough improvement to warrant an upgrade.