Bounties wont never end not even in this current market condition where all the price of cryptos have fallen . maybe the op is just blind because he didnt see any new bounties that pops on this forum and on other websites as well .
If you mean that bounty ends in the middle of ICO, probably the ICO successfully reach the hard cup .
Well thats not always the case on why a bounty can be ended on the middle of the campaign bcause most of the reasons are possible fraud . the project is fake and they have been busted because some memeber have taken an investigation and reported them .
and if ever the ico had already reach their cap , they will always have an announcement just before they run their campaign . its usually indicated at the title of their thread .