I appreciate the creative thinking, but I'm not sure this trade makes sense for either team involved.
Tyreke doesn't make sense on the same team with Isaiah Thomas and Marcus Smart, not to mention that his lack of shooting or defense on the wing wouldn't exactly help the Celts in areas in which they are weak.
Ryno's shooting would help the Celts with their weaknesses in that area, but he's not a playmaker at all and Stevens likes having guys at the 4 who can create for others. Ryno is a pure 4, too, and Stevens doesn't seem to prefer guys who lack positional versatility.
Not to mention, this trade would kill the Celts' cap space pretty badly, and Danny Ainge values flexibility too much to do it.
For the Pels, I just think this would set them back too far. This may be a lost year for them already, but I don't think they'll be willing to punt on next year, as well.