Cap trouble Tampa

You are right to think that Tampa is both a) looking to move Callahan and b) potentially looking for a RHD. However, there are a few issues with this trade:

1- Callahan has a partial NTC allowing him to select 16 teams he'd be willing to be traded too, I can't see him uprooting his family to move from Florida to Colorado.
2- Tampa would only move Callahan if it was necessary to keeping Point. Even then they would either buy him out or move him to the Rangers for picks/prospects, not an important roster player.
3- Tampa is not going to trade Brayden Point, especially not for a return that is 2/3s future pieces. Tampa would trade almost every other forward on their team to make room for Point. Point is a young forward who is incredibly fast, has Selke potential, plays on the top power-play, plays on the penalty kill, is top 10 in points, top 5 in goals, and still on his ELC (albeit the final year).
4- While Barrie is fantastic and no doubt a player every team would love to have, he isn't really the type of player Tampa is looking to make a trade for. If we are to believe rumors, the Lightning were looking at Martinez as a potential addition and Miller was rumored to be the player going to LA. Martinez is a guy who kills penalties, hits, blocks shots, plays both sides, etc. Tampa already has one of the top scoring defensive groups in the NHL. While adding Barrie would absolutely improve Tampa's defense, he just isn't necessarily what the team needs right now.

In summary, I think you are correct in what Tampa is looking for (top 4 RHD). But, you're incorrect in what Tampa would be willing to give up to in a trade for said dman. Unless I'm selling Barrie short on his defensive abilities I can't see Barrie being the guy Tampa pursues.

Ive posted a trade very similar to this and i would love to get Point on COL but TBL fans all said that Point is untouchable and TBL would make any other moves necessary to have the cap space to sign Point (which is the right thing for TBL to do in my opinion)