Yes, it's true, the murderous, sadistic 'Islamic State' will be history, and very soon. Why? How? Saudi Arabia is the short answer. The only Arab Muslim Superpower (although they keep that title under wraps, it's true). The Saudis have themselves to blame, in part. They are the ones who funded the expansion of extremist 'Wahabism', the most restrictive and conservative version of Islam. Wahabism embraces traditional (neolithic) Arab culture, as a standard of behavior, dress, etc. etc. It stresses silly things like "What is Islamic?" basically stating that everything invented or discovered after the death of the prophet is "un-islamic", and goes from there. (as for instance, the Saudi cleric who issued a fatwa stating that the world is flat-in 1985!)(Although we have a few Christians in the US who have similar views).
Back to Saudi Arabia, they will never let some jumped up loony declare himself 'caliph', they hold the keys and won't give them up. They hold a huge part of the collective Arab/Muslim purse, and again, will not share it with a delusional thief.
Finally, the IS itself is a coalition of groups, and sharing is not an Arab cultural norm, the groups will argue over who gets what soon enough, and will stop killing women and children, and start killing each other.