I am no expert on the Princely Family and I also don't like speculation, but I think that it's possibly too early at this stage to come to a concluded view as to how Caroline's role will now develop.
Much as we all deplore tabloid trash reporting etc, on a worse-case basis, if the tabloid rumours about fresh paternity suits etc are true, and unpalatable as it may be for us to think this, if Charlene decides that she no longer wants to remain in the Principality, then Caroline's presence will continue to be important. This is how I see it possibly developing:
Like I said, I don't want to speculate unnecessarily and neither do I want to take the thread off topic, but I feel that 'this tale is not yet told'. Princess Grace arrived in the Principality unable to speak much french and she found a very different life waiting for her and to start with by her own account she found things very hard. But at least she did not have to contend with paternity suit rumours etc. The success that she made of her role is truly inspiring. Fast forward to this summer and I keep looking at the wedding photos and to me the overall picture is that Charlene did not look a happy person. Who knows what she is experiencing behind the Palace doors? It did chill me to read in The Times that Prince Albert's aides were united in saying that [if the paternity rumours are true,] then Charlene's duty is to support Albert; well that is ok up to a point, but I would have preferred it if they had been able to say 'These are completely untrue rumours and Prince Albert will be suing'. Instead we hear of Princely displeasure with the Palace moles etc. Sneaking is deplorable, but it would have been unnecesary if the rumours were without foundation! If, therefore, it then turns out to be true and that Albert had concieved a child [or perhaps more than one] at the same time as his relationship with Charlene, then I foresee great trouble ahead and I can almost see Charlene leaving the Principality [regardless of whether she did so just before her wedding] and rushing home. Caroline will then find herself charged with the responsibility of holding everything together.