You do not need to repair any devices if you backup your CC253x to an image file and restore that image file to a new CC2652 based adapter, (with that backup and restore method you can even migrate from Silicon Labs based adapters and vice versa). The migration procedure is shortly described here:
You do however usually have to power-cycle some or all of your devices that do still not connect even after you left it alone for a while, (then easiest for mains-powered Zigbee devices is probably to start by just temporary pull the main circuit-breaker for the house/apartment in order to power-cycle them all).
Specifications on ITead’s website is wrong, so see correct specs for Z-Stack_3.x.0 on CC2652P here:
CC2652 can have 50 direct children = 50 direct attached devices, and each of those 50 directly attached devices can route another 50 devices, but in the end, 200 is the maximum of Zigbee 3.0 devices.
So in theory, it should be able to control 200 new Zigbee 3.0 devices + 1000 older Zigbee Home Automation 1.2 devices at the same as Zigbee Home Automation 1.2 devices have almost no overhead.
The 200 limit for Zigbee 3.0 devices is because security for Zigbee 3.0 devices have a lot of overhead.
Poor advertisement as yes the CC2652P hardware does support 20 dBm transmit power, however the current firmware is configured to use 5 dBm transmit power (same at the hardware limit for CC2652R).
It now sounds as ITead will work with the community to make a firmware for it that does 9 dBM because that will result in a dongle that achieves less than 10 dBm in ETSI spectral density test and that is a requirement for commercial certification.
Meaning even if the hardware can do 20 dBm to transmit power, ITead can not legally sell and ship it with firmware a higher transmit power configuration if they want it to get commercially certified.
There is however nothing that is stopping you from building and compiling your own firmware configured to use 20 dBm to transmit power and then flash that, though it would be illegal to use in most countries.