It's not so much that they are enormous economies, it's that they should be relatively easy to set up Free Trade agreements with. India, Pakistan, Sri Lanka, Australia, NZ, South Africa, UAE, all strong friends and allies of ours, generally English speaking, pretty similar laws and institutions, and all with many cricketers who'd be keen to spend their summers in England earning GB£. Personally, I think the effect could be seen not only at County / T20 Franchise level, but further down the pyramid as well. Right now it is not easy for an overseas player to get a visa for a summer just to play for a club, and generally if they get one they cannot get allowance to work and earn - no NI number either. This could easily change as part of post-Brexit agreements.