I'm fairly sure they've expressed somewhere along the lines that orange essence and things related to them won't be changing, apart from them adding bad luck protecting from chests so you'll be guaranteed a skin shard after enough champ shards in a row.
What they said about things going down in value was the disenchant value of champion shards (not skins), since leveling up gives capsules which are likely to contain champion shards, meaning people will get alot more champ shards than currently. Champion skin shards and ward skin shards should have the same value, and would continue to disenchant into the same amounts of orange essence though, so it shouldn't matter if you use them now or later.
It is worth it to disenchant any champion shards now because their disenchant value will be going down, but again, that's just the base champion shards and not champion skin shards.
Honour just provides a more reliable way of gaining key fragments, which are only really useful for the chests we get from our weekly S ranks, so it's extremely unlikely they'd change that.
edit: Actually I'm wrong, they're tuning down all the disenchant values.
https://support.riotgames.com/hc/en-us/articles/115012640908
Are you making any changes to the way disenchanting shards works?
Since you'll be getting more shards thanks to the new leveling system (and with other recent changes to honor and events), we'll tune down the relative value of the essence you get from disenchanting shards of all types—champ shards, skin shards, and ward skin shards.
In the current system, for example, disenchanting a champ shard will get you about a third of the BE you need to buy a champ at that shard's tier. In the new system it'll get you 20% of the way there. Also, with so many more champ shards in the system, we need to remove the ability to reroll them into permanent champs—but we’ll occasionally sell mystery champions for blue essence. For these reasons, you should go ahead and reroll or disenchant any shards you don't want to upgrade before preseason hits so you can get the most essence possible out of them.
To make up for essence drop rate changes, we'll tune the way loot boxes work to increase the amount of skins you'll get from them. We'll also add "bad luck protection," so you won't ever go on long streaks without getting a skin shard or a gemstone from chests.
So disenchant everything you want to disenchant now. Purchases probably won't change though (as they'd only need to tweak either of disenchant value or orange essence costs, not both, in order to keep things consistent), so I doubt it matters when you do it for ones you're planning to 'purchase' by way of upgrading to permanents.
