One thing to note is that life expectancy is not necessarily still increasing across Canada. Life expectancy for men in BC for example was 80.5 in 2015 and fell to 79.9 by 2018. I have a feeling it's about to get worse. 170 British Columbians died of an overdose in May alone.
If we push back the OAS age while life expectancy falls we're accepting lower living standards for poor seniors.
I bet lower OAS clawbacks could save tons of money. Seniors are the
richest age demographic in Canada and they make up a growing percentage of the total population.
But I think UBI might work well too, which runs contrary to OAS clawbacks. My main complaint isn't so much that OAS is extravagant, it's that it's misdirected. We balk at benefits for working poor with a very low quality of life in Canada (e.g. can't get dental work done because it's not covered) but for some reason it's acceptable politically to pay out OAS to seniors with millions saved and a six-figure income.
Note that there is also the Guaranteed Income Supplement on top of OAS, but that has a very low income threshold ($18,600 for an individual; but I don't think it counts wealth). It tops up OAS paid out to people who only lived in Canada for 10-40 years as an adult. So if you were to hypothetically immigrate to Canada as a 55 year old, you could live here on savings for 10 years then collect around $18k a year. Maybe Meng Wangzhou will qualify if we hold her long enough and her accountants manage things right.