If the majority of Singaporeans are against the PAP, it won't make a scrap of difference how the boundaries are drawn.
The fact remains that the PAP is the most popular political party in Singapore by a country mile.
If that were the case they wouldn't bother to redraw boundaries. Political sentiments fall into 3 categories - anti , indifferent and pro. My feeling is the pro is about 1/3 as reflected by the last presidential election. Anti is about 1/3 and growing. Nobody knows how the indifferent will change but I doubt they will break for the pros.