Not quite. Dropped Artifact (purple) gear come with two mod slots, Enhancement and Modification. Presumably they'll come with artifact quality mods in those slots. What they won't drop with is an Armoring (for armor, effects the armor rating)/ Barrel (for ranged weapons, effects damage output)/ Hilt (for melee weapons, effects damage output) slot.
Now by the sound of things there will be "best in slot" drops for those specific mod items that you could then put into any moddable piece of gear, and end up with an item that was equal to a dropped item for that tier.
Once the next tier opens up, you'd either have to replace your modded item with an artifact drop from the new tier, or simply replace the mods themselves with mods from the new tier.