Darsh to open, Warner to four.....To be fair Handscomb and Marsh really haven't made that many more runs than Warner. Marsh has made 146 for example to Warner's 131 in the same number of innings. Average of 24 vs 21. That doesn't tell the full story because Marsh has played two innings that are better than anything Warner has and I think it's reasonable to expect openers to score the bulk of the runs in India, but Warner has made a lot of starts, and was a decent contributor in Pune with that opening stand that set the tone for the series. He's had a bad series but I don't think he's in any danger of being dropped and it is possible to overstate his failures. It hasn't been on the level of Kohli's series, or Ponting in 2001 or anything. And there's no reason to categorise Warner's performance as drop-worthy but Marsh's as a good series worthy of praise.
Warner's subcontinent failures are a problem for sure and he does need overseas runs, but he's such a monumental asset in more friendly conditions that I think by the next time a tour to a place he's likely to struggle rolls around (when even is that? 2019 ashes? He's not even that bad in England, and I don't think there's a winter away tour next year) he'll have made more runs and cemented his spot in the team again. I'm not sure when the next time he's even like to play on slow, turning wickets is. Australia have toured Pakistan, India, Sri Lanka and the West Indies all fairly recently.