It will get too big one day but probably, hard drives and SSDs would be much cheaper so everyone would still be able to afford running a full node. The reason why most people don't support bigger blocks is this, people will no longer be able to run a node and only big companies will be able to so, so the network will be less decentralized and we don't want that.
Don't you think that by the time we reach a blockchain of a size that is considered too big (right now) we would have found methods to store more data on less for a relatively cheaper price. I'm not really a geek when it comes to hard drives but when I put together my pc in 2014 the guys from the store I was purchasing my parts from told me they were getting shipments of hard drives of 4-6TB. Surely in 10 years it will be quite common to have a hard disk of 10 TB or even more?