There is however no technical reason we should limit the blocksize to 1mb. We could have 10mb or even 100mb blocksizes easily. Realistically a 100mb block would be large enough to handle all transaction data our species currently generates.
The transaction fee is a considerable portion of miner's revenue. Miners ultimately are responsibility for making changes to the bitcoin protocol. I think it's unlikely bitcoin miners will vote for a higher blocksize because it will cause short term decreases in revenue. However, they are missing a potential boon from the Jevons paradox -- the cheaper a resource becomes to use the more of the resource we use.
So in summary, it's not really a technical limit to have a high transaction volume but we aren't likely to see it from the current big coins.
