NZ really stepped up when I was delayed in HKG and would have missed my TK connection to IST (on another ticket). They placed me on another carrier without me having to ask.

There was just a thread in the UA forum, though, where a mechanical delay on an IAD-GRU flight last week led to many passengers missing their LAN connection to SCL. UA refused to help.

It depends on the airline and probably who you speak to.