Progression

Tiers

At this point, tiered gear seems likely and was mentioned by the developers.

It was also stated though, while every piece of gear can be equipped right away, your efficiency of using it will be key.

Acquiring gear

Available information indicates that the best gear will be sourced from crafting. According to the following developer quote, gear may also drop:

...Compared to most games, we plan to invert the value of loot vs player crafted items. We want to see the players creating the best and most valuable items in the game...