As far as I know, it isn't only the Lakers who are interested in DeRozan, but also teams like the Kings, Spurs, and Heat. But in the case of the Lakers, the problem is that they remain in a big financial bind. Given this, I have doubts that they will be able to sign a player like DeRozan.
If they were not able to sign Klay, then it's unlikely they will sign DeRozan either. Klay received $50 million for a three-year contract with Dallas, but DeRozan made $50 million in the last two seasons with the Bulls based on his average yearly salary. So, we are talking about a larger amount here, especially considering DeRozan played very well with the Bulls last season.
That's another problem not unless DeRozan will adjust maybe they can work it out or they will accept the liabilities in exceeding with their cap maybe it will materiaized they need to negotiate and find all the possibilities, in terms of performance if DeRozan will be added to them he can provide decent numbers though coach and teammates have that specific roles to execute and manifest his position.
Like what you said, another big name that will be traded to a different team which is interesting as he will be playing with LeBron and AD a good star who can help carrying the team if another bad injury will happen to either LeBron or AD or even both, DeRozan can take charge and lead the offensive side.