David Greggory, which sits on a prime corner in the burgeoning West End, will close in early August and reopen by mid-September as Hudson, a Contemporary American brasserie named for the explorer Henry Hudson. Greggory Hill will remain in the kitchen of this new venture, but there will be a new owner, Alan Popsky (Felix), who plans to transform the setting into a loungey go-to spot for anything from a take-out breakfast to a client dinner to a post-theater snack.