Are there any projections about when transaction fees per block will equal block reward? A spreadsheet with a base projection and the following editable variables (for a given block height) would be great:


BTC transaction volume per block 
Number of transaction per block 
Average transaction fee


Please assume that most BTC transactions will remain on the main chain (and not on a lightning network or something similar).
You can find out the average transaction fees gathered per block here. You can see that it's been slowly increasing recently, and there tends to be a block every year or so that skews the average quite a bit. But we can confidently say that currently, the average fees per block is around 0.35 BTC, which has increased from about 0.15 BTC of a year ago. Assuming a linear 0.2 BTC increase in fees per block per year, and a 4 year halving schedule we get these equations:

fees = 0.2 * x + 0.35
reward = 0.5^(x/4) * 12.5 


Reward is a discrete function, so we can just see what happens at the halving in 2020, 2024 and so on.

2020:

fees = 0.2 * 4 + 0.35 = 1.15
reward = 0.5 * 12.5 = 6.25


2024:

fees = 0.2 * 8 + 0.35 = 1.95
reward = 0.5^2 * 12.5 = 3.125


2028:

fees = 0.2 * 12 + 0.35 = 2.75
reward = 0.5^3 * 12.5 = 1.5625


If it proceeds like this, it looks like there actually won't be a moment when average fees and reward actually equal each other as the reward will halve and will be bypassed by fees at that point suddenly.

A different (linear or non-linear) function for fees will obviously achieve different results as would the block halving time being a bit shorter than 4 years, but this projection does make it seem as though 10-12 years is around when fees and reward will approximately meet.