The murmuring has been going on for some time and I think Haley is trying to make a case for replacement. Personally I don't see any concrete upside to replacing Pence and a lot of concrete downside to it. Trump would be a fool to replace him, and while as a politician Trump is unorthodox he's shown that he isn't a fool.
Haley is just selling her book and tossing red meat to the MAGA base. Pence has been pretty much useless but I don’t see POTUS replacing him. Haley is young and playing a long game here. The GOP bench post Trump is incredibly thin and most potential GOP POTUS candidates have beltway stink on them.