Next game or (next couple of games), I want to see:
Chadli-Holtby-Lamela
Holtby deserves a start and I would really like to see Lamela.
However, I wouldn't go against replacing Chadli for Siggy ... as I want Siggy to get more game time so that he can improve to give better competition. Yes, Siggy can also get time in the EL, but IMO EPL experience is different. Plus, the next two games are against the so-called more winnable games.
As for the long run, I want to see:
Lamela-Eriksen-Lennon
... when the team is having difficulty breaking down teams, need width, and Eriksen because he will give balance and compensate the width for introducing more of a goal threat that may not be there when playing natural wingers than opposed to inverted wingers. Plus, Eriksen IMO is more comfortable at spraying diagonal through balls, etc (than Holtby).
Chadli-Holtby-Lamela
... when the team needs goals, against wide playing team, and Holtby because if there are inverted wingers who tend to stay up front more and may expose the wings, we need a playmaker who is a less of a goal threat so that he tends to stay more deeper and drift out to the wings if need be. Plus in such cases the defensive work rate is a great asset.
Holtby fits this perfectly from what I seen, where as Eriksen is more of a full-on CAM.
But, here I think the nature of the gameplay will make it become more of a 433