What will happen to IB Internships after British Exit?

Hello everyone,

I'm a English person from London currently studying Economics and minoring in Math at university in the US whilst playing on their D1 soccer team, I am also going to enter my Junior year in the fall.

As a result of being on an F-1 student I am only allowed to work in the US for 1 Year after graduation and if I were to do an internship at a US based bank then it would eat into that year, so I have been planning to try and get an internship in a London IB next summer as this won't reduce that year I can work. However, after the British exit result it seems getting an internship for next year is going to be harder that ever, so what would your advice to me be?

I could just try and get an internship in the US but this would hurt my chances after graduation. I could also try to dual major in Mathematics as well this would give me 3 years instead of 1 that i can work for after graduation but this wouldn't be funded by my academic or athletic scholarships, so it would cost me about $15k extra should I do this?

Thanks for your help.