I'm passionate about getting a secular education for my sons. I don't like the trend of the past 10 years where they cut it out of mesivtas.
My hope is that since this isn't a communal "shitah" (like chassidishe communities), rather just inertia - that it would be easier to get mesivtas to offer it again.
What would you want them to learn?
Most important is to read English that is the key to everything else.
I see absolutely no reason to teach more than reading and writing English, addition, subtraction, multiplication, division, (fractions too for all 4), basic algebra. A few basic useful mathematical formulas.
The rest is likely a waste of time.
If there's any leftover time it would be much more useful for them to teach how to fix things in day to day life.