rising processor power -> "uncrackable" sytems become crackable
And "Security by obscurity does not work very well either." Which GSM party relied on as well.
One the people who specify standards that involve *security* elements will realize that a standard that does not expect to *evolve* over time will become obsolete.
DES was the classic case of this.
So 3G is *supposedly* (IE when security features *properly* implemented, switched on and configured) is more secure, but for how *long*?
Remember DES? secure in its day but probably used *long* after people from the NSA down could crack it. Only deprecated when the EFF *built* hardware to prove a crack in < 3 1/2 days was *well* within the budget of crime cartels or successful terrorist groups (or < 3 1/2 minutes if you're Elon Musk and wanted to get a *whole* lot richer fast).