It is a bit naïve to predict a Tokyo/Shanghai style grand and super vibrant street just because more condo towers are added - Bay is full of condos and remains largely boring and deserted. The reason Tokyo and Shanghai can achieve that level of vibrancy - huge population aside - is that most of towers are commercial/office, with large numbers of high density residential neighbourhoods nearby (Tokyo actually has few skyscrapers, Shanghai's condos towers are usually not that tall either), as well as small boutique stores (with less prominent location and cheaper rent) and restaurants on each and every side street nearby. What are to be constructed on Yonge are predominantly tall residential towers - but with similar amount of retail as - if not less than what it is now (and we know much of it will not be interesting but only to serve the condo residents - for example, I will never go to Yonge/Wellesley for a RBC or a nail salon).
If we look at all the successful big names streets in the world from Tokyo to Istanbul, from New York to Barcelona, none of them is predominantly residential and height is hardly relevant. I am not against the towers replacing current ill maintained houses on Yonge at all, but in order to achieve a high level of vibrancy (Yonge/Dundas and to a less extent Queen W/Chinatown are the only place I can call vibrant. I wouldn't call Yonge/College vibrant), you need large amount of retail - a mix of everything, from high end department stores to 711, and that should happen not just ON Yonge, but need to spread all the side streets within 5 minutes walking distance to Yonge as well. From what I see, however, that is not happening.
But more condo are at least a good start. Less embarrassing than what it is like now.