Catholics who are aware that the Catholic church is the One True Church do indeed put themselves in danger of Hell by rejecting what they know to be true. All others, YMMV.
The article states that she was considering attending another church, not that she was rejecting anything. Is it a mortal sin for a Catholic to attend a protestant church?
And by the way, what kind of grief will I get into on this thread if I state emphatically that the Catholic Church organization is presently in a state of visible apostacy and that the "One True Church" is not an organization, but the corporate body of true believers in Christ?