Hrs on this...

I would not change what you have now.  First, don't change something that is working (there's always the risk that it makes it worse or you run into new issues).  Second, there is newer Wi-Fi 6 technology coming (6E) so better to wait and upgrade to a newer tech once it is available and also stable vs. downgrading.  Your current system offers better flexibility than depending on wired and it's unlikely that your throughput is limited due to wired vs. wireless backhaul.  Many of us run wireless backhaul just fine and have the convenience of placing our satellites anywhere and adding as we go along.  The newer AX systems may also be more particular than AC about having too many satellites or too close to each other (possible, suggested interference) further limiting you on your ability and flexibility of taking advantage of fixed wired port location(s).