The extension applies to the hardware as well as the support.  
Looking at 10th Gen Latitude 55xx series ... I see warranty options listed below.  Question.  If I pay for the 3 years ProSupport ..  does that extend the 1 Year Hardware Warranty as well?  I keep seeing the words "Support" and "Service" .. and not "Warranty" .. which makes me uneasy.  I don't want to have a logic board fail 2 years in and then find out that the ProSupport I purchased can be there the next day to fix it - but only if I buy a $1500 part - because the hardware warranty was only 1 year. Basic Service1 Year Hardware Warranty with Onsite/In-Home Service after Remote Diagnosis - Included in price ProSupport1 Year ProSupport with Next Business Day Onsite Service + CAD $63.903 Years ProSupport with Next Business Day Onsite Service + CAD $417.484 Years ProSupport with Next Business Day Onsite Service + CAD $602.085 Years ProSupport with Next Business Day Onsite Service + CAD $758.28 ProSupport Plus1 Year ProSupport Plus with Next Business Day Onsite Service + CAD $151.943 Years ProSupport Plus with Next Business Day Onsite Service + CAD $579.364 Years ProSupport Plus with Next Business Day Onsite Service + CAD $807.985 Years ProSupport Plus with Next Business Day Onsite Service + CAD $995.42
Confused - Does ProSupport include Basic Warranty?