I dunno about obsoleting LINQPad yet. Half the power on LINQPad is its UI; I'd like to see how comparable VSCode / VS are with dotnet run vs LINQPad.

IE: LINQPad has a great way to visualize results. If dotnet run only outputs text, or otherwise requires a lot of plugins to visualize an object graph, there will still be quite a niche for LINQPad.

In contrast, if all you're using LINQPad for is to double-check syntax, then dotnet run might be a better option. (Sometimes if I'm "in the zone" and unsure about syntax that I use infrequently, I'll write a test LINQPad script.)