If Dash ever gets a split it should be micro and not milli for future proofing.
A division by 1000 is too little. You need to think in terms of USD market cap (or even more). https://fiatmarketcap.com/
20 trillion dollar Dash market cap would make each Dash roughly 1 million dollars. Thus divide the current Dash price by a million.
Dash should be $0.0002 right now. We will moon for being super cheap. Salivating noobs will dribble all over us.
Being serious: Even a micro Dash is not enough for future population growth.