A couple news stories to update around: Putin allegedly getting cancer surgery and an assassination attempt in March.
Cancer: Putin allegedly underwent cancer surgery in April (https://www.newsweek.com/exclusive-putin-treated-cancer-april-us-intelligence-report-says-1710357), and there's been speculation since then about his health (https://www.newsweek.com/vladimir-putin-cancer-surgery-claimswhat-we-do-know-what-we-dont-1709689). He was allegedly followed by a thyroid cancer surgeon during his trips to Sochi, which is probably related (https://www.themoscowtimes.com/2022/04/01/putin-accompanied-by-doctors-thyroid-cancer-surgeon-on-sochi-trips-report-a77177). Also following him on the Sochi trip were two ENTs, a neurologist, and a dermatovenereologist (https://www.newsweek.com/putin-health-rumors-cancer-parkinsons-disease-russia-ukraine-1704211). There's also rumours about him having Parkinson's, which may explain the neurologist. There's also a recording of an alleged oligarch saying he's "very ill with blood cancer" (https://newlinesmag.com/reportage/is-putin-sick-or-are-we-meant-to-think-he-is/).
Most likely case to me is that he has thyroid cancer and has been undergoing treatment. If that's the case, it seems pretty unlikely that he'd die from cancer within the next six months. The overall survival rates for someone of his age with a typical thyroid cancer are very high, it only decreases a couple % per year (https://www.researchgate.net/figure/The-Kaplan-Meier-curves-for-survival-in-patients-with-differentiated-thyroid-cancer-DTC_fig2_303869859), and is >90% at 5 years. If he has a typical thyroid cancer with distant mets, the 5-year survival rate is 63% at lowest (https://www.webmd.com/cancer/prognosis-stage-iv-thyroid-cancer), or ~7% death rate per year. With 6 months left in the year that's 3.5%. He'd need a rare type or some other complication/comorbidity to make the prognosis much worse than that.
I don't put much stock in the other rumours, they're something to watch but they don't substantively impact my forecast right now. Putin having Parkinson's is based on some videos of him looking uncomfortable in a chair, which is hardly evidence of anything. A neurologist cited in the above Newsweek article says he "can find no evidence" of Parkinson's in the clip. The blood cancer rumour is from a recording of an oligarch, and I don't trust someone with mere Kremlin ties to know specifics of something as sensitive as Putin's health. It seems more likely he either didn't know the type, or Putin having metastases got mixed up in a game of telephone. If Putin is a 69 year old with blood cancer, he looks absolutely incredible.
Assassination: there was allegedly an assassination attempt against Putin while he was visiting the Caucasus shortly after the war in Ukraine broke out (https://www.businessinsider.com/putin-survived-attempt-on-his-life-ukraine-intelligence-official-2022-5). The main takeaway for me is that it was by "representatives of the Caucasus", not by anyone in his inner circle or even within Russia, so it doesn't indicate anyone is turning on him from within. Successful assassination attempts are extremely rare, especially outside of the developing world (https://en.wikipedia.org/wiki/List_of_assassinated_and_executed_heads_of_state_and_government). The risk is higher than baseline with Russia being in a more large-scale and costly war, but an assassination, especially within 6 months of the leader of a large country, is never very likely.
All that said, I do maintain a general uncertainty bump of about 5% with this much time left. That we would be in this scenario at all just a few months ago was near-unimaginable. The situation has been chaotic, and its hard to argue that an aging and cancer-afflicted despot waging an unpopular and costly war is a recipe for stability and no surprises. Uncertainty about how much longer he'll continue ruling may compromise the relationships that made for stability for the past couple decades, and may make Putin's risk tolerance higher than that of his colleagues (and may have already), leading to conflict. ~3% cancer death risk plus that bump puts me at ~8% for now, linearly decreasing to 0 by January unless anything else develops.