Hi
I think when ur parent card is valid until 2010 so no problem of going back to canada but problem will arise only when this card will expire before that if they want to live in canada he can not live there, he will have to renew his PR card from the canadian immigration authorities please check the address on website and contact them regarding this
The date on the PR Card means nothing, it is just date 5 years after the card was issued. To meet residency obligations, the PR must remain in Canada for 2 years in every 5. So the OP parents have probably lost their PR status. When they return to Canada, they will be most likely reported on arrival, but admitted to Canada for 60 days to appeal the loss of status. It is at the appeal that they would have to prove Humanitarian and Compassionate grounds were sufficient that they should be exempted from the residency requirement. If they don't , they go home. Suggest the OP read
http://www.cic.gc.ca/english/resources/manuals/enf/enf23e.pdf starting page 19.
PMM