when the Hero campaign end and BTS will reach the promised price, a whole lot of people will dump it for profit.

I honestly don't see a problem here, if BTS is $333ea then Bitshares will be on a whole other level with a $1.2 Trillion market cap...

The safest option is to sell for bitusd as it is a stable coin

HERO is a stable coin, it appreciates in value and is as safe as bitUSD. Likewise, HERTZ isn't unstable as much as it predictably fluctuates in value.

But since there are only 3mil bitusd most of them won't be able to sell because the supply will dry up. Maybe then your token will come in handy too

Indeed, hopefully HERTZ will be able to provide far greater liquidity than bitUSD.