As I said, there are a lot of weekend cars & pple who go to Plaza Angsana & Pandan market to save some money (besides the car wash & petrol saving crowd). These pple will definitely visit less. It may not be so immediately obvious to you, as you don't go to SG much, but a 20% drop is a big impact to businesses. As you said, see how it goes lor, but too bad for the daily commuting PRs. Being a weekender, it really doesn't affect me too much, even at RM 100.
But I just laugh at the naivety of certain forumers who think part of the money will go to improving JB roads/amenities etc, rather than 5th Avenue shopping sprees. I thought Malaysians are typically more streetwise.