I wish I knew, but I am sure they will reopen some time this year. They planned all along to pause and reopen all streams throughout the year in order to give people the chance to apply at different times throughout the year. They wanted to avoid last year's situation where they had already received enough applications in May to fill their 2016 nominations quota.
I doubt they will have filled their 2017 quota even after processing all existing applications. Unfortunately they haven't updated their statistics since July 10, but as of July 10, 3,515 nominations had been issued and there were still 2,485 nominations remaining.
http://www.ontarioimmigration.ca/en/pnp/OI_PNP_PROCESSINGTIMES.html
To have received enough new applications to fill the 2485 nominations in the 2 weeks that OINP was open after July 10, they would have needed to receive 177.5 new applications per day. That sounds excessive even in light of their statement that the HCP stream had recently seen a surge in applications.
I would say it's highly likely that they will reopen later this calendar year. They do list an estimated processing time of 30-60 days, but many on these boards, especially the ICT workers, have been getting their nominations within 10-30 days. Hopefully this means that they should finish processing existing applications, see how many more nominations they need to issue for the year, and be ready to reopen their system to new applications within a month or 2.