I think Challenge Gear should continue to be able to be crafted onto, but have a cap on the power level you can add. At the moment challenge gear is OK, but not a massive improvement over using random gen loot to level, except in the case of builds that use all the different types of elemental spells and the like. Having Challenge Gear receive a big upgrade with the Cannith update would make running challenges for players/toons who don't already have those items relevant again; if Challenge gear were changed to just have a new augment slot, Cannith Challenges would remain as dead or become even more dead than they already are, with them probably only be run for guild renown pots.
In addition, please do not switch any effects that have scaling versions into those versions. A big advantage of Challenge gear at the moment is that the spell lore on them hasn't been ruined yet by the idea that spell lore amounts need to be single digit in low levels, and that's about the only thing keeping the gear relevant (aside from blurry on the bracers at low level). Honestly, all lore/fortification effects on random gen should be modified from the current system that makes them next to useless in low levels, because those aren't effects that NEED to be lower in low levels.
Runearms can only be used on builds with at least 2 artificer levels anyways. The type of artificers that play with runearms I would say are probably behind on power anyways (Most arti's I know dual-wield for casting or use a shield) so the cannith crafting changes could be considered part of an arti buff. If it's still a big issue for builds like 18/2 rogue/artificer to gain big buffs from cannith crafting, make the maximum ML of crafting effects for runearms equal to 4+arti levels+epic levels. This would mean that an 18/2 rogue/artificer could only craft level 6 shards on a runearm at level 20, level 16 shards at level 30; that's still under half the potential levels. This also would mean that pure arti's can craft level 34 shards, which is the max in the new cannith crafting system, so the more artificer levels the stronger effects can be added to runearms.Runearms:
A similar issue exists with Runearms. Having 3 effects on an item which can then have 3 powerful crafted effects added is too much.
The most straightforward solution would appear to be that the charge tier, the spell itself, the rune arm imbue, the ML, and any very unique effects (such as Coronauch) would stay. The rest of the effects would be removed when prepping for crafting and then you could craft on 2 effects (or 3 using the Mark of House Cannith). The list of effects for Runearms is still being worked on.
Thoughts, comments? And as always, all plans are subject to change for any numerous and unforeseen reasons.
I'd say for runearms just copy and paste the list of effects from trinket's more or less.