The public ledger adds a new entry every 3-5 seconds. So I am worried it might grow too big for normal users to run a node. How big is the current ledger and how much is it expected to grow each year?
Won't be able to tell exact number, but this is not an issue.
Stellar has different levels of participation. Only archiver and full validator nodes publish archive and maintain full history.
Also this archive doesn't need to be stored on the server, it can be published to S3 bucket or any other cloud storage.
Nodes keep current state of the network and can be configured how many ledgers to maintain using stellar-core configuration option