There is no reason for there to be a ceiling just 2 years in.
Newey and team cand find 2 seconds easily. And if they dont find more pace, they will find a way to make peak pace sustained for longer on a long run.
Remember Max has complained about the tyres this year. As dominant as the car is, it still has some flaws. And flaw is relative because even when it's not in the optimum window RB19 is still miles ahead of the other cars.