If Deno was only "Add TypeScript support", "Add security capabilities", and "Add URL imports", etc. it would simply be a new version (or multiple new versions) of Node.
These (and other) disruptive breaking changes are about fixing mistakes that cannot be fixed (or at least, are hard to fix) in Node.
Maybe, in a few years, you'll say something like "Oh, I wish legacy Node would be more Deno compatible" because Deno will be the de-facto server-side JS scripting runtime. Equally, it's possible that Deno will fail, but that many good ideas will be incorporated into Node as breaking changes.
Node and Deno as well as their environments can grow further together or further apart. I think it's too early to tell which future is more likely.
These (and other) disruptive breaking changes are about fixing mistakes that cannot be fixed (or at least, are hard to fix) in Node.
Maybe, in a few years, you'll say something like "Oh, I wish legacy Node would be more Deno compatible" because Deno will be the de-facto server-side JS scripting runtime. Equally, it's possible that Deno will fail, but that many good ideas will be incorporated into Node as breaking changes.
Node and Deno as well as their environments can grow further together or further apart. I think it's too early to tell which future is more likely.