Personally, I'd love to see Maria play doubles. NOT at grandslams so in those she can focus on her singles. But at random smaller tour events. So like USO series. Or whatever she plays between AO and IW. It can improve her confidence at the net. Her reflexes etc so I think it'd be beneficial for her.
I'd love to see her play with Vesnina again.
Or Wickmayer. Remember when they were about to play together and couldn't get a WC