are you taking the positive externalities of cryonics into account?

I'm not taking them into account, but mostly because I think they're small. The cryonics wants to be big article is only concerned with the storage costs, which I think are not a big issue. The big cost currently is in preparation for freezing, not the keeping cold. (Freezing and preparation is ~$100K while long term is only ~$100/year (so $10K if you can get 1% real return).

Hanson's article brings up more issues, which I think is good.

Even if cryonics became massively popular, however, we'd still have several problems: we don't know if we're preserving all the information, we don't know if it will ever be possible to extract the information, we might kill ourselves off first, it might never be cheap enough to revive a significant fraction of those frozen. These concern me enough that I think inducing others to sign up might actually be negative because it's redirecting money from current spending to what I think is probably a waste.

the world of today, where cryonics is weird and marginalized

The way I see it becoming normal starts with adoption by the scientific minded rational atheists who are it's most natural audience. This group is going to be (rightly) skeptical unless we can do a freeze/revive round trip on a person. (EDIT: I've backed off from this claim some downthread.) I don't see us getting to a world where cryonics is normal just by signing up and encouraging friends to do so. What I see as most promising, actually, is the continuation of low temperature medical research that has no intended cryonics application.