Beginning next year. This is not new. That was the case pre-1994.
Of course we will continue to visit JB. To tourists and visitors it is a non-issue. The hotels, shops, food joints, restaurants and recreation outlets like KTVs, massage spas, reflexology centres will always be open for business regardless of what day it is.
This only means that instead of Sat & Sun, they will have Fri, Sat & Sun as a holiday. Although they say Sun is not a holiday, in practice they will relax on Sunday. Johoreans will have more fun and enjoy life more.
Just don't show off your money or behave arrogantly and you will (usually) be safe.
As to whether Singaporeans will visit JB more often will depend on whether:
• Singaporeans got more money to spend.
• Singaporeans are attracted elsewhere - say to other competing nearby destinations.
• JB has more recreation outlets that Singaporeans are looking for.
• JB crime rate againsts tourists/visitors
• currency exchange rate bewteen SGD and Malaysian Ringgit.
It has nothing to do with whether Friday or Sunday is their official holiday.