Good question, thanks for asking it. I didn't explicitly address this (oops) and I'll have to do some more thinking. My first reaction is that:
1) Svelte gives you a solid foundation and lots of flexibility
2) difficulty scaling for large apps is mostly orthogonal to the component library
3) Svelte provides flexible and sugary integration points for these orthogonal concerns
For example, since we're talking large projects, the biggest concern is state management. Svelte is like React here, in that you could use MobX or Redux with a connector library, or RxJS with Redux, or other combinations. As long as your solution is compatible with stores like RxJS is, you benefit from Svelte's auto-subscriptions[1] and sugary store dereferencing[2] that's agnostic to your underlying state management solution.
1) Svelte gives you a solid foundation and lots of flexibility
2) difficulty scaling for large apps is mostly orthogonal to the component library
3) Svelte provides flexible and sugary integration points for these orthogonal concerns
For example, since we're talking large projects, the biggest concern is state management. Svelte is like React here, in that you could use MobX or Redux with a connector library, or RxJS with Redux, or other combinations. As long as your solution is compatible with stores like RxJS is, you benefit from Svelte's auto-subscriptions[1] and sugary store dereferencing[2] that's agnostic to your underlying state management solution.
[1] https://svelte.dev/examples#auto-subscriptions
[2] https://svelte.dev/examples#readable-stores