if they had stayed engaged, I think CW still would have succeeded. Perhaps I am being too optimistic! I agree with some of the other postings that CW would have been eager to make his fortune, either to marry Anne in the first place (if they had decided on a long engagement) or to provide for his family (if they married fairly quickly). Maybe he would have been more afraid of sailing on the Asp, if he had something to lose. But he has been described as such a confident young man at the time he met Anne(LR did not like this confidence, she thought it out of place considering his lack of fortune and connections) who knew he would succeed--perhaps that confidence and determination would be have been able to carry him to success, instead of having to rely on his broken heart to do the same.
One thing I am sure of--had CW been married or engaged to Anne at the time, Dick Musgrove wouldn't have written such disinterested letters to his parents--CW would have had too much on his mind to worry about Dick's character and family! ;)