I open another thread about it because I honestly think people fantasize on the idea that Apple is going to continue the MBA and release somthing really cool and affortable... I am convinced that the 2017 MBA is the last one. Apple could release something else with another name also however as we discussed here the next "MBA like" (if they release anything!) will be quite diffferent for sure (so different that it would not make sense to keep its name - its name does not make sense anymore in 2018. "Air" was refering to lightness but the new MB are thinner and lighter.) But in my opinion Apple is busy trying to fix the issue withe MB and MB pro and will not release a complet new model (it's fantasy, even if we all hope for that)
Apple always wanted to have 2 categories : Macbook and Macbook Pro. The air was an exception.
Also as I explained in another thread, Apple is trapped because their more expensive Macbook are barely faster than the 2017 MBA and cost much more. To me they are not going to release soon anything because otherwise nobody would buy their Macbook. And if they do, it would have to be as expensive or more than the current MBA (but their mac are already all overpriced with a lot of issues). The 2017 MBA is definitely are must have because it will be the last Mac with a good keyboard, USB, magsafe, still very light and pretty and powerful as well. Last but not least, it is also the last mac that you can replace part inside yourself (i.e : SSD, etc). So if you spill on you keyboard you can still replace it (I believe), etc. It is not the case with the new mac!
To answer your question, you could wait, it won't kill you but Apple is good at making people wait for the next release that never come. The 2017 MBA is an excellent machine but still overprice... However, you can get good deal or find cheap second hand (there are always good deal if you are patient), this is what I did.