At this point it would not fail, it may be relegated by a newer service, like IBM and Xerox gave way to Microsoft and Apple. The big old corporations are still there, but they are not what they were in the 1980s.
Or if there was a big technology shift to something they have not yet mastered they could be made irrelevant, but still exist like Kodak.
They are too big to fail unless it is by their own failure to adapt or bad financial decisions (look at Blockbuster, Borders and Polaroid).