Control the temptation and save the money. Let this notebook become less than you need and then spend the money on something that will be fit for your need. Current notebook suffices. That is what I told myself too.
Invest that money, let it grow. In 2-3 years time, that money thus invested will only serve for helping you upgrade when you really need to upgrade, not merely want to. The reasoning of doing what you want, there is only one life, goes only so far. There is joy to be derived out of saving and watching that money grow instead. For me, that money was too much ($2300 at least) so I was better off just investing. It helps that I write, and edit photos, so my use case will not gain too much from a quad core, to justify my spending $2300 today. I feel, I will be more satisfied with a res bump than just these evolved goodies of 2018 notebooks, for my use.
I could spend some money and go for a new 2018 notebook (coming from a 2016 13") but there is no value in the new notebooks for me good enough that I cannot have on my 2016. I will upgrade when there is a screen res bump, not before.