4 shops closing down would also equal 4 empty premises - your calculation assumed that those empty premises will stay empty - which is illogical as in most cases premises will be up and running give or take in 1.2 months.
therefore, assuming - based on your theory that in 10,000 years 146,000 restaurants will go bust, the most coherent deduction would be the churning of 146,000 new businesses. and by safely assuming only 50% of them are in the food business - total restaurants generated by the establishment of 3,650 mamak restaurants would be - 73,000.
to illustrate further, assuming that all 73,000 restaurants are in the area of PJ as one of the highest density area in malaysia, it is most possible that you would find one tom yam shop every 663 square meter - against one mamak shop every 13.3 km square.
apart from that, you might also want to include another variable to your observation- the fact that for every 3 tom yam shops going bust - 5 new ones will be opened.
so there. you might have established a good theoretical framework, but the calculation model is wrong - for the most part of it. mamak will never take over malaysia, there will always be tom yam establisments or medan ikan bakar somewhere around.
thank you for making my sedantary day more interesting.