GT-AXE11000 is BCM4908 and Linux kernel 4.1 (older Broadcom SDK).
GT-AXE16000 is BCM4912, Linux kernel 4.19, and newer Broadcom SDK.
Asus hasn't officially announced their plans for these older models, but my personal opinion is that chances of them moving to 3006 at this point are very slim. The cutoff isn't randomly based just on the age, it's also related to the software and hardware platform itself.
That does not mean the end of support for these models. 388 will still receive bugfixes, and possibly even a few enhancements, judging at how Asus did that in the past with the 382/384/386/388 series. Heck, devices that have been EOL for 10 months now are still getting occasional bugfixes.
Asus router owners have been spoiled IMHO by the fact that they often get brand new features to their existing devices. This is very uncommon in the market of these AIO home routers, where new features are generally only reserved for new models.
When you bought the router initially, it was for its existing feature set at the time. Any future feature addition should be taken as a bonus, not as granted.