If this 2am closing sticks, and it has done in the recent past for a whole high season, it isn't necessarily bad for anyone but the discos. People will start to go out earlier, smart bar owners will make sure their girls are in the bars by 8pm (a good policy regardless of the closing times, 'Hello' to the first two bars on Soi Lion duh) and the party starts earlier.
The discos on the other hand suffer badly as they really only make any money after 2am.
Bar owners will find that their bar girl staff become a little easier to control, a lot more punctual and work a lot harder if the only place they can pick up a punter is in the bar they actually 'work' in.
When the discos are open all night, many staff are using your bar as somewhere to hang out, get a free loom and food until the discos get going, so bar owners should rejoice. You are no longer subsidising the discos.
I fully expect the situation to return to normal, maybe even before I finish this response, however, if it doesn't bar owners should be very happy.