On Linux the only option currently is to run MT4.
It is possible to go to VBox and Windows but many users of Linux will not take that security risk. (being attacked from within)
Your Portable solution is a huge step forward when combined with WINE+Linux.
As mentioned MT4 already works well.
1) NinjaTrader + data feeds
2) TradeStation + data feeds
- are just two - you are guaranteed to have people interested.