An unofficial website with a fleet overview of Lufthansa has now updated the status of D-AIHT to “Reactivation @ TEV”. D-AIHT is an Airbus A340-642X operated by Lufthansa and has been stored in TEV since May 2020. That would mean that at least the D-AIHT or even more A346s could return to Frankfurt in December or January! There is of course no guarantee of correctness, but the source is often updated and is mostly correct.
In response to my request, the Lufthansa social media team has not yet been able to give official confirmation, but it has not been denied either. Nevertheless, this is a good sign and we may be able to fly real routes from LH in Infinite Flight with the A340-600 again next year in January! :D