Most important question first: Who is the primary applicant? You or your wife?
If your wife is the primary applicant, and she chooses not to land and 'activate' her PR, then you cannot land and activate your 'PR' either (primary applicant must land before or with the dependent).
If you are the primary applicant, it doesn't matter. You can land, activate your permanent residency, and if your wife and baby don't land, they won't become permanent residents, but you will be fine. (As stated earlier, you will also have to meet physical residency requirements - 2 years physically in Canada within your first 5 years of landing).
If you wife and baby do land and 'activate their PR' then leave, and don't meet their physical residency requirements, this won't affect you either.
Once you become a PR, you can do whatever you so choose regarding your marriage, including Divorce, without any negative implications to your PR Status (I don't think Canada is trying to dictate our family lives and make-ups
).
Although, if I may be so bold as to ask a question and offer some advice: if you've already made the decision to divorce your wife once you land, have you discussed this with her already and aren't waiting to do so until after you land? It's just that, if you haven't told her, this might be blindsiding her and I'm sure you wouldn't want her to make the decision to give up her great job and move to Canada, for the sake of the marriage, only to be served with divorce papers a short while later. I personally fully support the idea of divorce if a marriage isn't working despite efforts to make it work, and one or both parties are unhappy, but I also think it's important to ensure that it's an open and honest process, and that every effort is taken to ensure both parties leave the marriage in the best state that's possible for each of them (after all, I'm sure you owe that much to each other after all the time you've spent together
)
Also, just from my perspective, if I shared a child with someone, I would want to maintain at the very least a cordial and respectful relationship with my divorced partner, for the sake of that child. And this will be particularly important if you want to sponsor the child for PR later (if he/she doesn't land and claim his/her PR now, or if he/she does land but doesn't meet the physical residency requirement and ends up having his/her PR revoked), as I suspect you would need your wife's permission for this if the child is still a minor when you decide to sponsor him/her.
