>the salary structure in baseball makes it cheaper to invest
>in African-American-like Latino players....

You're smart here to identify reasons that impact both supply and demand for black players, though the latter has some changes on the horizon that could (emphasis on "could" not "should" or "will" and definitely not "are intended to") even that balance a little bit. An MLB draft for international talent has the potential to reduce the value of scouting far off reaches of the world for cheap talent because those players will still be subject to the whim of draft order. Feels like the possibility of an international draft has been such a common feature of recent CBA negotiations that it's kind of inevitable. On the other hand, it'd be a "solution" to this problem that mostly works by taking away negotiating power from international players, which is counterproductive. If the international draft is going to help black players, it'll only do it by hurting other players - and I think just ending the draft entirely would get the same (or better) traction without the harm.

People in Puerto Rico have, for a long time, claimed that the inclusion of PR in the MLB draft in the late 80s adversely impacted youth baseball development there because it reduced youth players' negotiating ability, which reduced interest in developing youth talent, which reduced the amount of good players, etc.

This won't impact the salary structure once signed, which in basic shape resembles most other sports (young players are more controllable by their team and are therefore paid less) but which exaggerated by how discrete and particular baseball skills are to develop. Or, put another way, it's more common that a 21 year old can start on an NBA team than on an MLB team.

>Add in factors like how expensive it has become to play youth
>baseball in the US putting it out of reach for most
>African-Americans and its so much more too...

This seems like a far more complex problem to solve, because MLB teams can't be relied on to invest in players that they don't control. So that process of player development, etc. is farmed out to youth leagues and high schools and colleges. And that dynamic is bound to mime current social and political and economic trends.

So the sport's future in the US is in the hands of people who need to watch out for their own financial security, and that's contributed to a flood of talented and helpful skills coaches and youth leagues taking the wheel for player development. But those aren't available in every area (particularly areas without ample green space and nice weather) or affordable for every parent. So the game is basically turning into hockey or lacrosse at that level: way more avenues to success if you live in a wealthy suburb and have at least one parent constantly available to ferry you from practices to games to private practices with particularized skills coaches. And there are plenty of black American families that have that, to be sure, but it's a numbers game.