>>12277065Well, if rockets get to really gargantuan sizes (like 18m Starship) then Raptors really won't be able to cut it anyone, so many of them would be needed for a first stage booster that even if they were 99.9% reliable the chances of one having a catastrophic failure would be close to guaranteed. At that point a new very large form factor deep throttling booster would need to be designed.
One benefit of improved manufacturing does seem to be a reduction in turbomachinery size, Raptor's pumps are quite petite and even if you increased it's size into F1 ranges, like the F-1B it's turbopumps would benefit in reductions to size and complexity thanks to modern manufacturing and material science. You'd probably need something like 24 F1 sized engines to hoist an 18m Superheavy.