What will likely break the monopoly is a Chinese competitor producing a worse but usable product within the next couple of years. AMD will be the next Compaq.
But Nvidia isn't inept yet, and despite some of its people being just as arrogant as Googlers at Google's prime, they still deliver a vastly better product and ecosystem than anyone else. The Chinese will crack that, but the first few generations are going to be a rough ride. Just check out the iterations on any knockoff of DeWalt tools they sell with cheaper parts until they nail the price/performance ratio to perfection to see how they roll. But also, Nvidia remains a moving target with near bottomless pockets now. Good luck with that.