I don't think there is anything to save. Technically besides very important updates to keep it working - s2member has been dead for years. It's rather important to get out of it as soon as possible and to find the best alternative.
Essentially s2member is 2010 not 2018 tech.
Plus Stripe is for example not supporting Stripe Sources - so the more mobile dependant your business is - the less it actually works already right now. For many websites it's essential to have Alipay, Apple Pay, Google Checkout or similar offered via Stripe Sources. Stripe sources make it way easier to support different payment options instead of supporting each payment gateway on it's own.
Right now it's only China where people think WTF is a credit card, I want to pay with my mobile phone via WeChat or Ali/Tencent - I guess soon this will apply more and more to Europe and America too. Paypal is still important in Europe - same as actually for old people to support bank wire (easiest through something like Giropay or iDeal and similar - all supported via Stripe Sources). With s2member right now checkout is way too difficult for new generations and not quick enough. Besides Content protection I don't think there is anything worthy to keep.