Hi all.
You should not be too concerned about operating voltages with the sly card, if you consider the range of boxes these cards will have to interface with and the chance of Sly having to spend obscene amounts of money from card failure which could additionlly damage the actual box, then a reconsider would be in order.
A standard micro used in a smart card application would be capable of operating at a wider range of voltages than most would consider, 5V being the standard which most receivers have operated from for a considerable amount of time, dropping to 3.3V would be within the operating range of the card, this would be for speed rather than anything else.
In the forseeable future, manufacturers will change to lower operating voltage for these cards but these would be for other applications than satellite as no one could guarantee the boxes operating voltage and considering the operation of the card it is very unlikely these manufacturers would ever want that is capable of an increase speed.
I did actually try to kill a smart card several years ago when I was bored and managed to increase the operating voltage to just over 16V before it started to not respond to commands.
Any additional temperature from the card would solely be from more electronics increasing the ambient inside the box or other issues and bear in mind that if the card reached a level that would cause failure you would not be touching it or anything in its vicinity
Lastly, as we have the ever infamous 'Amstrad' building the boxes for the + range, I would consider the change in operating voltage voltage be a very long way off.
If you feel unhappy about this, add a fan or two