diagnosticator1

fluid that is oxidized and has experienced changes to viscosity and pH balance, etc, is preferred compared to fresh new fluid that hasn't suffered deterioration from the harsh conditions of operation
By not changing the fluid, none of the benefits of improved fluid properties available since the original fluid fill can be taken advantage of either.
In addition, there is no factual basis to assume that increasing amounts of wear material left to accumulate in the trans, is the preferred conditional state for the trans, as compared to limiting the amount of wear material in the trans by regular fluid changes.

The reasons for the trans fluid being considered "lifetime fill", as stated by ZF and Audi, is due to marketing and maintenance cost concerns, not by the technical facts involved.
The big picture from the manufacturers perspective, is that the lifetime fluid fill will provide satisfactory reliability for the average vehicles typical operational period, the statistical probability of failure being very low, and costs of repairs to the few that fail early, will be cheaper than a fluid maintenance requirement for the fleet, and often will be post warranty anyway, so cost of repair will be the burden of the few owners effected.
The reduced reliability and service life that results from the lifetime fluid fill, is not relevant in the decision to establish the no maintenance required policy.
Regardless of the situation behind the policy of no fluid changes required, regular fluid and filter changes will be beneficial to the durability and performance of the trans and for most cases,* extend the useful operational life span far beyond the average trans that has never had the fluid changed since new.

IHTHS

*A small number of transmissions will fail earlier than the average anyway, from some non fluid related malfunction.

A4_Jax

after all, i went by Audi's maintenance schedule! since i plan to own the car for only another year or two, should i go through the trouble and expense? if the transmission does go by the time i'm outside of CPO warranty, i probably wouldn't spend a couple of grand to repair a car that's only worth like $6k.

user 7208203

Why not just recommend a change at 105k or 150k instead of saying lifetime? That costs them nothing.

I agree changing fluid will do no harm, but there is a point at which is excessive and wasteful. (not to mention costly) Why not replace engine oil, antifreeze, spark plugs, air filters, fuel filters, tires, brakes, and tranny flud everytime you fill up for gas?

The answer will never be know without speaking with a reliability engineer at Audi, and getting a peek at their MTBF data.

Merkin

because if it fails before the interval they will have to goodwill it somehow

diagnosticator1

the standard deductable/co payment.

My perspective regarding the fluid changes is from the "drive it until the wheels fall off" point of view. If you are planning on selling the car soon, then I see no benifit to
you from changing the fluid, as a practical matter.* If you sell to a private party, maybe you could mention the recommendation to change the fluid, despite the offical lifetime fill policy as a courtesey.

*However, if you change the fluid before selling, that would be a benifit to the buyer, and raising the selling price to partially offset the expense would be justified.