Don't bloat XD. Sketch are the winner in the category just because it does what you need to and nothing more and it does everything perfectly.
Be honest, look at what Sketch does and take from that. The video that surfaced when Comet was announced was perfect. All it needs is what Silver (now owned by InVision) promises for Sketch).
Why do we need support for Indesign and Photoshop files etc.
Keep it simple, do it beautifully and we will come.
Thanks for your feedback! We’re looking at keeping XD lean and focused on designing and prototyping. Message heard, loud and clear :)
Chris Waldron commented
Can't edit posts. Sketch almost does it perfectly, so long as you take out that holding the shift key doesn't contain things very well when moving objects either horizontally or vertically (there are other gripes but can't think of them right now).