Those are great questions and we will see that when the platform releases. Withdrawal fees are not set in stone and can easily be adjusted depending on the situation. I have seen other exchange changed their fees based on the sentiments of its users as well as on the rates of other exchanges. Transaction fee mining has its merit but it also some drawbacks. There is  a reason why CMC excludes exchanges that use them when ranking exchanges. I am sure that depending on market demand these types of incentives will be considered by the management of the site. Although transaction-fee mining looks good for some investors I am not sure of its long term prospect for the sites that are implementing them. In fact binance CEO and Huobi CTO has called out exchanges that are doing this and expressing their disapproval of the practice. Personally i have tried this on another exchange it was profitable for a awhile but when the hype is gone so does the profits.