I suppose it depends on what problem you use TypeScript to solve. If you're writing a complicated and self-contained system, sure, I can see the appeal of "upgrading" to Java. If you're trying to enforce contracts between different codebases/libraries/etc., WASM hardly provides a better alternative: integrating with other libraries—especially JS ones—or even the DOM is non-trivial.
Which is to say, using TypeScript as a quality of life improvement to provide autocomplete and checking for easily-detectable bugs is not going to lend itself well to being replaced with WASM. If the goal is to write a 100% typed codebase (e.g., having a complex, entirely self-contained tool that runs in multiple environments), you will have better luck. But I suspect the number of folks that could benefit from that are fairly low, because it assumes that JavaScript is the bottleneck for correctness and performance. But if the real reason why you're using TypeScript is that JavaScript was your only choice and you like the increase in safety, having a more appropriate language could be an even more attractive option.
Which is to say, using TypeScript as a quality of life improvement to provide autocomplete and checking for easily-detectable bugs is not going to lend itself well to being replaced with WASM. If the goal is to write a 100% typed codebase (e.g., having a complex, entirely self-contained tool that runs in multiple environments), you will have better luck. But I suspect the number of folks that could benefit from that are fairly low, because it assumes that JavaScript is the bottleneck for correctness and performance. But if the real reason why you're using TypeScript is that JavaScript was your only choice and you like the increase in safety, having a more appropriate language could be an even more attractive option.