This is a new development and I don't think we can predict when this shift will actually happen or either it will happen or not. DeepSeek has to improve it's performance first to get global adoption. There is already a stable AI competitor standing in the market i.e. ChatGPT and if DeepSeek was not able to improve it's performance then it won't surprise us that AI users will prefer ChatGPT. User first interaction is with the interface and majority of users are not much interested in whats happening at the back end.
Even if DeepSeek's performance isn't nowhere near as comparable as ChatGPT's, it's still the most cost-effective GenAI on the market. It's no wonder why Deepseek is so popular. OpenAI should just open source the latest version of ChatGPT to stay ahead of the game. Otherwise, it will be seeing its demise soon. Same as Nvidia (although being a GPU manufacturer gives it some hope). For what I know, anything can happen in the future. So long as AI doesn't become a threat to humanity, there should be nothing to worry about.
