There's no need to talk about it, honestly. The last movie was satisfying enough that fan speculation / "theories" seem unnecessary. Spoilery garbage-tier clickbait will get shared around on social media anyway.
Disney should have just saved money and put a 30 second screen containing the title and release date. Anyone who saw the last installment will need zero enticing to see the followup; even people annoyed with how Avengers 3 ended will still eventually go to this one to see the ending after hearing friends hype it up.