Atmega328p mounting options
A couple of things.


I assume you mean "DIP" not "PID" for the existing package.
That socket you link to is not for mounting TQFP, it is for PQFP packages, also a very old package.


In my opinion, there isn't a good socket for TQFP packages, any you find will be expensive, have a large footprint and be unreliable - especially if you have much vibration.

If the change is just because customer opinion - what are they requesting?

Physically changing the device is an outdated method of performing updates - you need a mechanism for downloading an update into your product with no physical changes required.

You may want to keep the hardware Arduino compatible for ease of software development. Since you will need a serial port (or equivalent to download updates) there will be essentially no extra hardware required.

You can encrypt the image and have the bootloader decrypt so keeping your security. There are multiple options for a secure bootloader.


Microchip has an application note covering one that supports AES (you may have to use the AVR studio framework to use it): AVR231: AES Bootloader
This one looks interesting as it is very small: One-Way-Loader
Just Google "encrypted bootloader avr" for more options.