One answer might be to use BOTH platforms simultaneously, at least as a temporary solution. For example if WWG creates a Subscribestar this month, current Patreon subs can end their Patreon sub at the end of June and then just hop on Subscribestar, if they are able to, for July onward.
This would at least be a temporary solution for WWG to release Chapter 10 at all while still receiving backing. Would this be fair to Patreons who (for whatever reason) can't use any payment method successfully on Subscribestar? No. But at this point no practical solution has been proposed where WWG can keep his income, as well as release Chapter 10.
Also at this time almost everything being proposed on here is speculation. WWG might just be able to release Chapter 10 through Patreon, as planned, on June 11th or 12th. Unless WWG says anything before then or at that time, that's still the plan.