It is already possible to encode any file to the block chain(BC) cryptograffiti let people encode images, and it was never used for those purposes. Few places worse than BC to do that.
as I know cryptograffiti limits image size up to 50 kb 🤷♂️
Since it transfers to Dust addresses it takes about 4 bytes to encode 1 byte of data, and the dust is locked away forever, so it is a bit wasteful compared to memo and other OP_Return.
Yes, because it encodes into one transaction with a lot of output dust addresses and it do not use OP_RETURN, it is possible to split files into multiple 50kb chunks.
With infinitely long messages it is possible to just paste the raw text of the file anyways, there would need to be some sort of decoder anyways built into a service like memo.cash.