Max will continue to win races, but depending on how much the new regs bunch up the teams (if at all) and depending on all the other factors at play, Max could easily get to 30 and have been in a good seat, but not a great seat, its happened plenty of times before.
Remember Fernando after he left Renault the first time as a freshly minted 2x WDC. Who could possibly imagined at the end of 2006 that he would go on to race for Mclaren, Renault again and Ferrari before again going to Mclaren before retiring, only to win 17 races in 12 seasons and 226 races! Alonso won 15 other F1 races, in 4 seasons and 71 races before he left for Mclaren.
Silly season 2020 is going to be interesting as fuck. Right now Vestappen, Hamilton, Vettel & Riciardo all have contracts that expire at the end of 2020 with potentionally very big reg changes coming the very next season.
Yup, people tend to forget how many factors are in play when talking world championships. Everyone kinda just assumes Verstappen will beat all records, but to do that he'll need to be sitting in a world championship capable car (which means best car or only a couple tenths behind the best car - you simply can not make up a one second difference with skills alone) for at least 10 or so seasons, which is not a privilege many drivers got in the history of this sport. Hamilton and Schumacher had such a car for long enough (percentage-wise, Lewis probably had the most races/seasons in top tier cars), but so many others didn't.
Alonso was arguably the most complete driver throughout 2008-2013, and yet he ended up with a whopping 0 titles in that timeframe. Raikkonen was absolutely dominant for a while, and yet he only has one title next to his name in only about 5 seasons where the car was close enough to the title-winning machine. Mika Hakkinen was perhaps the driver who'd be able to challenge Schumacher the most in terms of drivecraft and mind games, and yet, after his 2 titles he endured two hit and miss seasons only to retire from the sport altogether. Meanwhile, Vettel sat in a dominant car for almost 5 consecutive years, and indeed he walked away with 4 easy titles, even in years Alonso (or Hamilton) were driving a lot better than him.
Or let's talk about how being in the right car at the right time brought titles to people who never really would have won in any other circumstance. Button seemed on the verge of retiring from F1, only to accidentally find himself in a dominant car and win a title after having a whopping 1 race win next to his name prior to that season. Nico Rosberg also never looked like he'd escape the "great but not among the best" driver tag, only to narrowly beat Hamilton in one of the most dominant cars of the past decades after a bit of luck with reliability and stewarding in particular. Or shall we talk about Jacques Villeneuve who narrowly beat Schumacher who was driving a considerably slower car - and indeed after said title his results have been rather hit and miss?
If Max keeps being in cars like the current Red Bull, that is cars that are capable of fighting for race wins (hardly ever in a dominant fashion) about half of the season while the other half he's lucky to fight for 3rd, he will not win titles unless some major fuckery happens at the rival team, something akin to McLaren 2007 (intrateam battle costing tons of points), Ferrari 2008 (driver, team and reliability issues), Benetton 1994 (the penalties), Red Bull 2010 (tons of points lost to retirements from the lead), McLaren 2005 (same). We can argue top teams will be having a bidding war for him, but nobody will know before the first races who's got the best car, and by then it will be too late to change an on-going contract.
Nobody expected Renault to practically disappear after 2006. Nobody knew Red Bull will not compete for a single title after 2013. Nobody knew Ferrari wasn't gonna win a title for over a decade after dominating the last one. Nobody knew McLaren wouldn't be scoring a podium for years. People laughed at Lewis joining Mercedes as it was a mid-tier team, then he won 4 (soon 5) titles with it. And so nobody knows if Mercedes will stay dominant in the next era or struggle to score points. If Ferrari turns dominant again or just stay close to the lead like the better part of this decade. If Red Bull can become a contender at every venue and not just sometimes. If some other team pulls out some unexpected magic like Brawn or Red Bull in 2009. Max could win 10 titles or 0, and much of this is not in his hands. If titles were awarded to the best driver each year, the Formula 1 stats would look rather different.