Certainly Ibra can play multiple positions well. Ultimately, it's a question of where is he most useful in a particular squad.
For a squad that isn't great at advancing the ball into the final third, he's more useful dropping deep to help move the ball up (it's impossible to take the ball off him and his passing/dribbling are very good).
If a squad had great midfielders to perform this role, he'd be much more deadly spending more of his time bullying the box, scoring goals, occupying defenders to create space for others, etc.
I'd like to see him paired with someone that can complement Ibra regardless of which role his in at any time. If he drops deep to CAM, I'd like to see someone who can exploit the empty space behind him. If he drifts wide, I'd like to see someone who can occupy the CBs physically. If he stays at the tip, I'd like to see someone who can drop deep to collect and advance the ball toward the final third.
Essentially, someone who can play S/SS/CAM. Essentially, Jovetic.
Now, here's an interesting question. If we had Ibra and Jovetic, who would be the ideal third attacker? A workhorse like Prince? A fantasista like Cassano? A nimble mover like Robinho? A finisher/poacher like Pato? A winger like Robben? Or someone who can do it all like Rooney? I haven't thought about it much, but I'm leaning towards a true trequartista+fantasista like Totti/ADP/Rui (can't find one today). Maybe Eriksen, though he's nowhere near the aforementioned players (and I'd likely want to see him in midfield instead).