I have wondered about this.

I have a a very superficial knowledge of trading, financial instruments, and crypto currencies. However, I am aware that over time large trading firms have been decreasing the activity of or shutting down completely their arbitrage desks. These opportunities were disappearing because of improved transmission of information between trading floors across the world.

Are there, for the time being, a new world of arbitrage opportunities between exchanges?

I imagine it would be a risky business since exchanges can and do close. To trade arbitrage across exchanges, you would automatically being increasing risk due to being exposed higher numbers of exchanges.