Since a roof is priority, don't consider just the fear of buying a property that might depreciate in the short run. In general, property prices MUST rise, may not be immed but surely in the long run and buying for own stay will assure the long run appreciation of prices. More impt considerations include
1. Can you finance the monthly instalments
2. Accessibility to the house since your kids will be going into sch over the next 5 yrs as well as amenities conveniences.
Resale HDB is always good option but comes with loads of regulations like MOP. As you rightly pointed out, you may miss out on the next downturn in economy. Heard that such cycles comes every 7 yrs and the last one ended in 2008. Next one should come in 2015 and your MOP will last through 2016. Ouch!
The attraction if you buy HDB is you have extra cash to invest in other things other than properties. I also agree that if ur kids are playing bumper games, its really time to move. Children today are so different from kumpung times when 5 kids can squeeze into one room. Anyway, it still comes down to your financial ability.
Another point I thought is worth considering is the fact that you want to wait till COV comes down. But reports after reports suggest that though COV is softening, the valuation of HDB is still going up. So the overall prices are still high... bottomline... no point waiting. You might loose out even more.
Also, are you confident in wanting to invest in properties after your MOP is up in 5 yrs? Otherwise, you could have done so now... i.e. not sell your HDB and buy another private property and rent out HDB? Hmm... Sorry for being so blunt... just my immed thoughts w/o fully understanding your situation...
All the best in your search. I agree with another person that the ECs are coming out more in Seng Kang Punggol area so its worth considering there. Prices will surely go up in the future...