I have some experience with handling a case where no standby service was available for my pet.  I know pets are not humans, but I think there is some insight worth sharing.  

If you can source dry ice, you can use this as a substitute for liquid nitrogen for about 6 months without suffering too much degradation compared to liquid nitrogen.  Generally, you will want to opt for this if you cannot arrange for transport to a storage facility within 24 hours of clinical death.  About half of all cryonics cases are "straight freeze" with no cryoprotectant, so there is a good chance methods will be invested in to revive those who undergo a straight freeze.  

My pet passed away suddenly two years ago after a failed emergency surgery.  I had her immediately transferred into ice-water bath after we could not restart her heartbeat.  About 19 hours later I arrived with a source of dry ice to straight freeze her until I could arrange transport to Switzerland for storage in Tomorrow Bio's facility.  I held her in a dedicated freezer with dry ice (replenished every other day to every two days) for about a month before I could work out how to transport her to Switzerland.  

From my conversations with Emil (CEO of Tomorrow Bio) this is very similar to their own procedure (as my pet was already under anesthesia from the surgery) minus the cryoprotectant.  So if you can have someone act quickly to cool your body to close to freezing then get you in dry ice for extended pre-liquid nitrogen storage you won't be much worse off than the other straight frozen cases.

For disclosure, I am signed up with Tomorrow Bio and this is my plan if my imminent cryopreservation is needed.  I live in a country with no standby service but figure this is better than nothing.

My personal assessment is that it's still worth it to sign up.

• Chances of a good preservation when you die unexpectedly are pretty low anyway and standby service isn't likely to improve that much.
• If you know you might die soon you can start paying for standby service (e.g. you get cancer or a serious illness).
  • But be aware you might get seriously ill quickly and become incapacitated before you can sign up, so this strategy mostly relies on having someone else who can sign up for you.
  • Also it's going to be more expensive. Usually the cost of standby service is spread out over years by being baked into the funding plan, and you'll need to come up with the money at the last minute to pay for it.
• If you can afford cryo now and think you'll be able to afford standby later, better to sign up for cryo now and then fund stand by later to get over the initial hump of signing up at all, as my understanding is that funding the cryo portion is generally the more legally complicated part anyway.
• Also, if you think cryo has a chance of working, some cryo seems better than none on the margin.

That said, standby is not that expensive relative to cryo (or at least it's not for me), and I think it came baked into my Alcor plan. I'm not sure how it works with CI, where the cost structure is different, but we should still be talking about a difference of maybe $10 or $20 a month if funded via life insurance.