I recently noticed there is no option to upgrade from Standard Shadowkeep to the Digital Deluxe Edition.
The issue is:
As of the writing of this post, Steam's regional prices don't quite apply to the in-game silver, causing silver to be very expensive when compared to the game itself.
What this means for me, is I would have to pay about 90% of what the whole Deluxe bundle costs, on top of what I've already paid for Shadowkeep, just to get the next three season passes. I can't speak for players from regions other than my own, but I'd assume they're facing a similar dilemma.
So at this point I'm wondering if the Digital Deluxe Upgrade will be made available to players directly through Steam with the release of Season of Dawn, seeing how regional prices clearly weren't taken into account when deciding to sell further season passes exclusively through silver.