I think they'll stop short of companion death - people do identify with the companion figure and they're aware of the number of children watching, some as young as five and six.

I think it can be even more powerful when his companions dump him. As in S3. What does bug me is that he's learnt so little from Jack and Martha's defection, if his behaviour in VOTD is anything to go by. Astrid was very generic and implied that companions are pretty replaceable.