The 2018 MacBook Air is not that much lighter or cheaper than the 13" non-touchbar MacBook Pro. The only advantage I can see is it offers the fingerprint sensor without the touchbar.
That said, neither is appealing, and the replacement I am actually considering is a 2018 Mac Mini (I mostly work in offices where monitors are available).
And I am also keeping my 2013 rMBP until it falls apart.
It's funny to see so many enthusiast rMBP users out there.
It's absolutely incredible how long my rMBP has lasted the thousands of hours of wear and tear of travel. At this point, my battery is pretty much non-existent and the body is a bit warped, but otherwise for a six year old laptop that's seen incredible amount of use per day, it's tremendously resilient.
It kind of disappoints me that five years after the release, today's batch of laptops aren't really that dramatically better for their premium cost, especially when you compare the difference between the 2012 rMBP to the 2006 MacBook line.
I also considered this since I dock my MBA most of the time and frankly even on the 2018 the graphics are incredibly weak. I needed some portability though.
That said, neither is appealing, and the replacement I am actually considering is a 2018 Mac Mini (I mostly work in offices where monitors are available).
And I am also keeping my 2013 rMBP until it falls apart.