Here's an odd idea.
Currently at end game Evoliths don't really stand much value and as far as I know they weren't mentioned on the roadmap of things to come so readjustment is unlikely or so one would assume. It's pretty much dead system when better gear can be obtained with less effort and completely devoid of extreme level of niche stats that is common with many Evoliths.
Yet it used to be what dev-team opened Synergy with and Synergy seems to be answer to every new recipe these days.
On the other end you have furnishings. Some use them for form, others for sheer function. They don't come with much stats at all except for good ol' Moghancement.
What if these two systems were combined? I'm not sure how much coding it would require or how much processing would it take to allow players to gain more than one stat from their furnishings. One can speculate how it would or would not invigorate hunting certain lesser known NMs or what effect would it cause on current decors. But I think Evoliths and furnishing could be a perfect match, to reinstall interest in an old system like Evoliths, promote Synergy (like a boss) and to come out with a new worthwhile system that players could spend time with.
Not really asking for a fish tank with Haste +5%, as there currently are no Evoliths that'd make that much difference. Existing Evoliths have way more niche stats to them than that but surely intriguing enough for players who want to excel at what they do to keep on trying.