I said iCloud could not be hacked today, given 2fa.
2fa is definitely a good way to go, it's smart and requires an extra layer of "something that you have, something that you know." As it will thwart many potential hackers, it is not completely fool proof. I had to take a hacking tools class during my Bachelors program to learn how these tools worked so we would understand what is necessary to defeat these tools.
The first thing my teacher said and I'm sure many others will agree with this statement is "If you can touch it, you can hack it."
The second thing he followed up with was "Depending on how hardened the system is, depends on how long it will take you."
2fa is nothing more than putting a fence within your existing fence (going with my previous analogy). There may be a hole in the first fence, but you still have to break through the 2fa fence behind it, if there is a known vulnerability in 2fa, the entire system is defeated, by hardening the outside fence (your stuff), you can reduce the number of known vulnerabilities in 2fa.