I think because of capacity of lipos and because of such high voltage , the only way to legalize lipos would be to set some wind limit ( like we had few years ago in TC in Erope 12 turn was the limit). And to extend duration of the race to ex. 7 min or 8 like in 12 class.
I think its quite resonable because most of us remember last TC WC in Italy.
In second round of A-main many drivers retired because of motor and chassis failures.
Thats why efra went to 5 cell's ... I personaly voted at EFRA AMG in 2006 to reduce number of cells to 5 (in name of Poland).
There is also a temperature issue when racing on lipos ,, more power = higher temperature of tires more wear , les grip etc.
Lipos are a good idea but only when racing with motor limit and longer race time.
I personaly think that 5,5 bl would be a good idea for a motor limit on 5 cells . ( carpet )