Sony & Microsoft:

-Sony will release a few first party PS4 titles, but the line-up won't be nearly as strong as 2018 first party.  Microsoft will release 0-2 first party titles for XB1 depending on how lucky their fans are.  Both consoles will continue to get strong third party support in 2019.
-Both companies will announce their next gen consoles in 2019.
-At least one of these companies will release their console during late 2019 or early 2020.

Nintendo
-Switch first party support will be somewhere in between 2017 and 2018 quality.
-Switch third party support is going to surprise a lot of people.  There will be about as many third party releases for Switch as 2017 and 2018 combined.  However, the quality of third party games is going to noticably better.  Expect more of multi-plat simultaneous releases.  Expect some third party exclusives.  Of course, there will still be some last gen ports and some multi-plat games that release on Switch later too.  Overall it's just going to be a lot of third party games of all kinds.
-Going with my above point, expect more than one Nintendo Directs with a "wow" factor.  Many people were "wowed" by Nintendo's September 2018 direct.  There will be more than one Direct in 2019 that is at least this good.  Expect Nintendo to release one of these "wow" directs during E3.
-Switch hardware sales are going to be up every single month YoY in every single region (Japan, NA, Europe, RoW).  The one exception to this may be December.  (See my next point.)
-Switch is going to be short supplied in December 2019.  In some areas they may be massively short supplied.  It will be very much like the Wii holidays during its first few years.  Expect the Switch to be that hot Christmas item that parents are desperately trying to get.

EDIT: I just want to add that peak year for Switch will be after 2019.  Either 2020 or 2021 will be peak year.

PS4 will sell 16M/16.5M units in 2019(thanks to a price cut in Sept), passing the 108M mark by end of 2019.
PS5 will be announced, and it will be a Monster.
X1 will sell slightly less, compared to 2018(like PS4); I'm not expecting a big decline.
XBox Scarlet won't be announced.
Switch will sell a bit more compared to 2018, but I'm not sure it will manage to beat PS4.

Interesting that you think Switch won't outsell PS4 in 2019. Considering it still might beat PS4 for 2018 (Almost guaranteed to beat PS4 in the US based on Projections, and demolished them in Japan.)

- Switch will sell 25m+

- Pokemon 2019 will get super hyped, but be bland, unambitious and lacking features from the 3DS games, as is Game Freak standard. (I hope I'm wrong, but nothing is indicating that I am)

- Town will actually be good, but will get drowned by getting released close to a much bigger game (Animal Crossing or Luigi's Mansion)

- Fire Emblem Three Houses is an April release, and will have three paths as in Fates, but intertwined much more smoothly. Gameplay in battle is along the lines of Conquest, but allows for grinding in between missions. Marriage and children will return.

- Animal Crossing will release in August, to great reviews and be a massive hit with ridiculous sales (25m+ LT)

- Luigi's Mansion releases in October. Will play more like the first game.

- Pikmin 4 releases in July. Olimar is back as the main character, has a treasure hunting focus like 2.

- Two of the remaining DLC characters are a DQ character (I'm hoping for Abel (the DQ V main) or Slime, but expecting Erdrick) and a gen 8 Pokemon

-Bayonetta 3 will come in September

- Metroid Prime 4 will have a big multiplayer focus, releases in November.

- Mario and Luigi RPG, codeveloped with Square, will be announced, will see the return of Geno and Mallow in some aspect.

Hey, I might as well throw a mad one in there, why not?

Games coming for me are Crackdown 3, Ori 2, Gears 5 and BATTLETOADS!

Also Metroid Prime 4!

That's interesting. I personally think Switch will outsell PS4 with relative ease next year. Though lets see what happens.

2019?

Switch does around 18-19m
PS4 does around 16-17m
XB1 does around 6-7m

I think in 2019 you will see official price cuts down to 199$ for both the PS4 & XB1.
Might be a reveal of PS5/XB2 as well (though they wont be sold until 2020)

Dreams, Days Gone, Death Stranding... and maybe Ghosts of Tsushima all release and review well.

Do you dislike indie games (in general)? And I'm inferring from your first point that it's happened before, but which games in particular?

Yeah I wouldn't say the Console market is doomed. It just needs to head toward Hybrid territory ala Nintendo. Cloud gaming will the next big thing. When that fully comes to fruition is unknown though. I do see a peak coming to the traditional console market coming and even Sony and Microsoft recognize it and are making adjustments accordingly.

People will overhype a games-as-service multiplayer type game only for it to be a disappointing shell of a game