This topic was mentioned a couple years ago about the non resident Canadian insurance cards being discontinued...
However when I asked my agent if the insurance company provider was still issuing them, he stated they still do so I still request them when I head into Canada in which I obtained the yellow card the past 8 consecutive years (and planning on going for 9 later this month).
What's inconvenient for me about it is my provider (geico) will not issue the yellow card to me by mail, I have to make a trip in person to the agent's office in order to obtain one as they hand write the information on it as it costs nothing monetary wise but a wasted 10 to 30 minutes for me depending how many customers they have in their office....although some insurance providers no longer issue the card, I will still obtain one until my provider no longer issues them, so technically as others have posted it is still the law to obtain one if they still issue those cards as to my guess for those insurance companies that no longer issue them must have an authorized status with Canada of automatic coverage per Canadian law requirements.
In 2013 I ran into my first road checkpoint in Canada 1 km west of the Cassiar Hwy. junction on the Alaska Hwy. where a Yukon RCMP detachment was patrolling along with wildlife officials - as I was asked what my purpose in Canada was (vacationing), where I was headed (unfortunately back home), and requested my driver license, proof of insurance, and vehicle registration.
I presented the ID, proof of insurance right away along with the yellow card as the officer told me she had no idea about the non resident Canadian insurance card as she never seen one before....
The officer would not clear me until I showed the vehicle registration in which it took me 3 minutes to find, as I was finally cleared only to get screamed at by other officers for me to stop as the female officer had to scream at the other officers to tell them I was cleared.
In my 26 crossings into Canada I was stopped only twice by officials and on one occasion at the Beaver Creek port of entry that a customs officer requested me to show proof of insurance, and neither of those times they specifically asked for the yellow card but they all wanted me to provide proof of insurance.
I'm with cruiser upon obtaining the card if they still issue them, however for those providers that no longer issue the cards I would not worry about it either but me personally I would request something in writing from the agent or provider upon not needing the card in possession since technically it is still the law in Canada to provide proof of the minimum requirement coverage for Canada.
