At this point, I don't think I'd trade Tatum for anyone, period. He has far too high of a ceiling and there is still too much uncertainty as to whether or not he will reach it, thus there is no way we could possibly get fair value for him in a trade. That, and I would rather see him in a Celtics jersey for the next 15 years anyway.
Brown, on the other hand, I'm more willing to trade. He looks like he will be a borderline All-Star for a number of years, but I don't think he has superstar potential. If we can trade Brown with an assortment of other assets for a superstar I'd do that in heartbeat. I'm just not convinced there is a team out there that would trade us a superstar without demanding Tatum, and as I said above, that is a non-starter for me and would end any trade discussion.
So, sure, if we could trade Brown + LAL/SAC pick + other assets for Leonard, of course I would do that. But I seriously doubt that is a possibility.