When demonstrative adjectives like this, that, those, and these aren't followed by nouns, they're not adjectives anymore—they're pronouns.
Your English teacher might tell you not to say "this" without a noun—"this argument" or "this book" or "this giant bucket of tapioca pearls," please. But, in the right context, it's totally fine. As long as there's enough context, that's what demonstrative pronouns exist for: to replace the nouns; not to add to them.