If ZoS were to solve the long lasting player gripe of overland difficulty in the right way - it could solve more issues as a by-product.

Let's say if a similar system that Diablo uses by having the entire world change to a nice variety of difficulty levels with increased loot drops/chances/gold rewards for quests etc, then it would do a few things as a by-product that could really aid players and the devs alike. However, as a caveat to that, it would need to be done in a certain way to reap all the benefits... If say, you cannot access those hard difficulties until your account has unlocked certain things (such as levels, or maybe completing some of the main story line at least once on your account etc), then having different world instances could easily provide the following benefits...

1) Less over populated instances reducing a lot of procedural lag/latency
2) Chat spamming from trader accounts that keep creating new accounts from banning/blocking by players would be highly reduced if the harder difficulties were gatekept as suggested above
3) Bot farmers couldn't easily access the harder difficulties if again it was gatekept - and nodes in harder difficulties could also drop more loot/resources from them, putting the power and control back into the hands of actual players once more.
4) Gold selling bots, like point no.2, would likely become redundant and less seen by players - meaning another issues semi-tackled by Zenimax.

Honestly, the possibilities are superb if it's done correctly... Any other benefits anyone can think of? I'm sure there are loads...