I don't see the downfall of Jack Monroe (the brand) happening any time soon however many people share the AM blog.
Jack has built a pretty much inpenetrable forcefield of 'tags' to ensure that nobody can criticise her actions without being accused of attacking her personally. Transgender, lesbian, non binary, gender fluid, ADHD, autistic, disabled, recovering alcoholic, single parent and 3rd/4th generation immigrant (did I miss any out?). Whoever aims criticism at her will be accused of transphobia, homophobia, ableism etc. etc. etc.
The blue ticks who have supported her will be unwilling to publicy distance themselves as it would be admitting they promoted a grifter to their followers. If Nigella and co. think Jack is the poor underdog patron saint of the pov then why didn't they offer to be patrons? I'm sure Nigella could spare a few bob to help her mate out so she's not reduced to tin rattling on Twitter.
The mainstream media is unlikely to pick up on this for various reasons including the fact that Jack is boring news fodder.
Jack will survive the AM blog and will seek to profit from the situation whether that's a pity party or a paypal payment. Her victim mentality will be difficult to suppress on social media. Some squigs will stop donating to her tip jar, others will put extra in 'to sock it to the trolls' and try to get noticed by Jack.
The AM article will have raised questions for some people and cemented suspicions for others. I suspect the majority of people sharing the blog will, however, already have been aware of her grifty ways. It's good that it's out there though.
TL;DR - Jack will Gloria Gaynor it through the AM revelations and live to grift again.