As someone who actually makes a living in HFT, if you really wanted to get rid of me, sub-penny ticks would be the single worst thing I can think of. There is literally no transaction tax that would make trading unprofitable. 2 zero's worth of decimilazation though and I have to go find honest work.

I'd only get rid of you insofar as you are fighting over latency. If you can deliver price improvement or useful market depth there is still a place for you.

I think decreasing the minimum bid/ask spread value would make it very difficult to continue doing traditional market making. I think that exchanges would then need to add some other incentives/perks to ensure liquidity providers stayed on their exchange, which starts to sound more and more like a specialist system which I'm generally against.

Of course, I don't think there is some natural right for market makers to exist. I do really like the idea of an extremely small tick size as it much more elegant than a transaction tax.

latency arb is still important to keep venues in sync.