According to BGWFans, they will be getting a very large coaster, 315 ft, in 2020. So it's very likely a giga.
I also see BGT getting a possible giga in the next few years. BGT had already wanted one instead of Cobra's Curse, but was shot down because the park wanted a more family friendly ride after Falcon.
Plus, in the earnings reporting, they said they plan to spend $150 million each year in capex. If they plan to spend that each year, they are going to have some major investments in at least a couple parks and then minor investments in the others. So far most of the rumors for next year's attractions seem to be small, which they may be starting that $150 mil in 2020 then. Unless SWT gets a major addition. They are more than likely getting something for 2019 it seems. Aside from that, BGT's Sky Rocket II and SWF's Sesame seem to be the biggest investments so far. But yes, the parks aren't broke. They are still very profitable, despite the last few years of bad stock/attendance. Bad attendance for a SW/BG park is a great year for a lot of smaller parks. They just hadn't been performing where they used to. Hopefully this good luck streak continues.