Predictability of renewables can be minimized via national grid interconnection. Even if it's cloudy and the wind is stagnant in one location, odds are that's not the case 500-1,000 miles / km away. The larger the grid, the more predictable renewables becomes.

Also, most Lithium-based BESS storage can discharge power to accommodate unpredictable renewables for up to as long as 4 hours, which can be enough to bridge the gap. If storage can't do it, the grid will.

And let's not forget other types of renewables + storage that don't care about clouds or the wind: run-of-the-river hydro (not reservoir hydro), pumped storage hydro, tidal, solar thermal, even wave although I highly doubt wave power will take off, etc.

The more diverse our power generation, both in type and location, the more predictable our grid will be. Diversity is key.

Edit: let's not forget about the other end of the power equation from generation: utilization. Energy efficiency and conservation through Distributed Energy Resource Management Systems (DERMS) are another tool to help the grid manage unpredictable renewables.