P.S., just to confirm my understanding: the tri-band mesh has a wireless backhaul which does not rob bandwidth from the devices and does not need ethernet backhaul, correct?
You got that right. What you want to look for is a dedicated wireless backhaul feature.
If most of your network devices support the latest 802.11ax (a.k.a. Wi-Fi 6) standard and you have a gigabit internet connection, there might be a reason to upgrade. If your current setup meets your needs, then I'd stand pat.
One note - it looks like all the TP Link gear mentioned so far supports the older 802.11ac (a.k.a. Wi-Fi 5) standard so you won't be future-proofing at all.