Hi,
Are you asking whether you can apply alone for PR (not apply altogether as a family) because of funds limitation? Btw, CIC requires proof of Canadian $10,833 for one person and Canadian $22,831 for 5.
But since you said you already have the file number then I assume that you already included your family members to accompany you when you move. For you to change anything (such as remove your family members to accompany you) on your application forms, you will have to explain why you made the change in a letter to the local visa office because your initial application has been assessed with different information.
Some Canadian visa offices allow applicants to submit proof of assessment of properties other than cash and so what you want to do is check with your local visa office on their website and see what options are available to you because you do have property worth Canadian $60,000 and you would like to use this property to show proof that you will have sufficient funds when you actually move to Canada with your family.
To answer your question -- what happens to their visa? -- If you apply as principal applicant and you include them in your application, then they will receive their visas when you receive yours. If you do not include them in your application and state that they will accompany you when you move, then they will not have permanent resident visas and only you will receive yours, because going by your intention, you would have applied only for yourself. When you are ready, sure you can petition for them to follow you later when you have established yourself in Canada.
Either way, whether you include them to accompany you or not, you will have to declare them on the application forms as your family members because if you do not do so, you will not have the chance to petition for them later.
Good luck!