The discussion about the wing depth is not very meaningful till we accept the fact that for good or for bad, we are likely to see lots of 3 guard lineups. Moreover, unless Bagley is traded, we are likely to see Barnes spend some decent amount of time there too. This of course assumes a healthy roster as currently constructed.
Even if we exclude TD, we have 4 guards who deserve and will command major minutes. Even if we argue that Davion is a rookie and yet to play any real games, the fact is that the team has invested in him, he is part of the future, and is expected to play a significant role by management and fans. Unless it takes time for him to figure things out, he will see minutes. So far at least, others have not made a case for increased minutes. Perhaps King/Metu will as the season progresses, but each of our guard (including Buddy, even Davion at the college level) brings proven, useful skills, and deserve minutes over current wings (other than Barnes). Given that Buddy is a likely trade bait, given our guard glut, showcasing him is good from a strategic perspective too.
If Bagley is healthy, he will see minutes at the 4. This is also good for us. We need to see if he is worth keeping, failing which, showcase him for a trade. Hopefully, he can improve his value in that case. That means Barnes will have to play 3, even if he/we prefer him at 4.
That doesn't leave a lot of minutes for King/Metu/Harkless. Yes, there will be games where some players will be off, some games that they will miss, etc., and hopefully they make a case for themselves. The team, as currently constructed, will not be able to find much time for our wings though.