I think New Vegas is ripe for a remake, because the negatives there are almost entirely aesthetic. The downside to that game outside of certain nitpicks, and certainly parts of the gameplay balance and the always-janky combat these games have, is it is just horrifying to look at, just horrifying. It's one of my favorite games ever but is just aesthetically repulsive, and it also was in 2009.
Give me a super good-looking New Vegas, with a super good-looking New Vegas City. Give me more robust-feeling combat that doesn't feel like my gun and the thing I'm shooting at barely even exist in the same game world. Keep the writing and gameplay depth otherwise intact.