Just to pause Jester David there to make it clear that here ends actual D&D RPG products. The rest of the list is figs, decks, 3PP products and even unrelated games.
The OP did as about "D&D" not "D&D the TTRPG". What I listed was still D&D.
And minis, spellcards, and the like can impact the tabletop game. You can spend your mad money on them, but there's no risk of rules bloat or power creep from miniatures.
If you need to know when more RPG material is coming out:
Green Ronin's
Book of the Righteous is out in May
Kobold Press'
Demon Cultes & Secret Societies will be out in June.
Nord Games'
Ultimate Bestiary: Revenge of the Horde is expected in May
And sooooo many more.
So what we know is nothing.
It's not nothing. It's three books. It's the exact same amount it was in 2015 and 2016.
They haven't announced anything, but we know it's coming.
It's reasonable to expect further product (as in one this spring and possibly two in the fall) but the difference between 5E's product schedule and the schedules of all editions before it couldn't have been greater.
Very true.
Y'know, unless you consider 1st Edition AD&D an Edition.
1e released the core rules once a year, then spent the rest of the time releasing small 16 and 32-page adventure. A year after the DMG they did a book of deities. Then they (kinda) had a new monster books. Another two years later and they did another monster book. Three years after that - six after the the last core book came out - the first new content for players was released.
The slow release schedule has been their "thing" for years. Since before 5e, when they slowed down 4th Edition's releases to a few key books. The current release schedule is very close to that of 2011 and 2012, when Mearls said they wanted to make each books special.