This is awesome to see. Coming from someone who lived up there for a few years and has seen the lows and highs like this before here is what I can remember from experience. Unfortunately that lake will never "clear" up like other lakes in the state, why I don't know but in the 20+ years I have fished that lake I have never been able to see more than a few feet down. Granted we have seen some dirtier water in recent years where even seeing a foot down isn't possible so it will have better clarity than before. I remember one of the times it filled and I did some exploring in the upper end of the lake I was amazed seeing lots of smaller crappie (visually) in the upper end in the spring chasing really small minnows near the surface. I mean tiny, no more than 3/4 inch minnows. My guess is the crappie migrate there with the flooded high grass and bushes to spawn and feed on the minnows and other aquatic insects and larvae that are plentiful when it fills. There is also a circular "hole" maybe 20-30 yards in diameter and much deeper than surrounding area way up there when it fills that used to hold decent numbers of perch and crappie. Overall, it's similar to the Carlos effect just without the size. Should be a lot of 10-12 inch crappie in there in there by spring 2021. Maybe even good numbers by next fall. Growth rate fluctuates depending on food supply.
Matt to answer your question yes, there will be pike, walleye and even some catfish that end up in lower Mary. And like the trout but not quite as much they benefit significantly from the new lake syndrome but unfortunately with the crack in the lake bed lower Mary doesn't hold water usually long enough for them to survive long. That being said we have been in a long drought so consistent good winters and monsoons could change that. Just guessing but if say 6-8ft of water makes it to the winter in lower Mary at the damn and there is a decent winter again that following year would probably be incredible for many species. Like fishless said the trout grow really fast, stock trout in the spring will be over a pound by fall. And if they put any incentive trout in there which they usually do those will be nice size. Occasionally they will throw some in upper Mary too but with clipped fins the pike seem to get them before anglers.
Take it for what it's worth, I'm no biologist, I haven't lived up there in a while, and my experience with that lake is dwarfed by many other experienced fisherman. Just my recollection of experiences I have had and seen over the years.