NOOOO.
I hide and sneak up on people in SG that is the point. Forcing a big pvp fight when only a few people are left ruins it. Some people win SG by sneaking up on people without them knowing, I and I would assume others don't want the end of SG to just be a pvp battle because then the person with the best items and pvp skill wins, not the person who is best at SG.
If this was implemented, I would just ender pearls away from spawn when it happened and you would still have the issue of not being able to find the people. It isn't a perfect solution, I much prefer zard's idea to make lightning start at 5 people left instead of 3.
This brings me on to my other point, you have lightning to find people at 3 left, why do you need them tped to spawn.
Finding people and sneaking up on them is part of SG, I don't want it turning into a pvp battle at the end.

 

This, this exactly.
There's no need for deathmatch.