No other company can. It is tremendously difficult to develop a GPU from scratch. Even Intel with all its might tried and failed miserably. There's always NVIDIA, of course, but when it comes to sheer compute power for the buck, AMD is the only game in town, as evidenced from their dominance in Ethereum mining benchmarks. That said, there are some algos that also play well on NVIDIA's Pascal architecture, so if those coins were to be "the next Ethereum", there could be competition in this market.