If we inspect the fees paid to miners per day in US dollars over the lifetime of the network (avg blocksize << max blocksize), we see that total fee revenue, on average, has grown with increases in the daily transaction volume.
The regression is dominated by increase of BTC value not that of fees.
The plot shows the total daily fees in USD versus the number of transactions per day. Indeed the correlation between the BTC value and the number of transactions per day is stronger, but that doesn't make the chart I plotted invalid. In other words, if the network growth in the future is anything like the network growth in the past, the total fees will continue to increase along with the number of transactions per day (and along with the price of a bitcoin).