So, if I am getting some of the implications of the release notes so far, it seems that:
1. Spells gem instances are getting a new way to differentiate from one another in addition to base type and tier (thus explaining why each individual spell gem is getting more importance)
2. Region tiers are being reintroduced (albeit in a different form, it looks like it will be per region "tier modifier" or something like that)
Now, this is merely inferring from the passing mention of these mechanics from some of the other semi-related entries. As of this writing, nothing about spell gem changes (beyond that they will now persist after being dropped) nor individual region tile property changes have been explicitly added as entries, so of course I could totally be wrong about this.
But if this is true, this will take care of one complaint (there isn't much "customization"/"optimization" players can do with spells, in part due to currently each spell gem of a certain type and tier is the same as any other spell gem of that type and tier) and reintroduce a popular feature removed during the beta (variance of tier per region).