Regarding "a level playing field for all market participants" I don't believe that in an exchange that supports HFT there can be a truly level playing field. There are some technologies that can help mitigate the effects of HFT on the market. One is the approach that AZX [1] took where you do large and infrequent dual auctions. Another approach is to go with an Automated Market Maker (AMM) technology and eliminate the need for order books all together as has become popular recently in the cryptocurrency space. Some background research can be found here [2] but what really took off was Uniswap's innovative use of a "Constant Function Market Maker" [3]. This allows average individuals to provide liquidity while getting the benefits of what is normally only reserved for high frequency traders. I believe that an institutional grade AMM program would be greatly democratizing for the industry.

[1] https://en.wikipedia.org/wiki/Arizona_Stock_Exchange [2] http://reports-archive.adm.cs.cmu.edu/anon/2012/CMU-CS-12-12... [3] https://medium.com/bollinger-investment-group/constant-funct...