First set of patches to allow changing the long double default were posted:

[Joseph Myers]

On Tue, 29 Sep 2020, Jonathan Wakely via Gcc wrote:

> I imagine C++  will want to support _Float128 at some point, with
> similar semantics to C.

Unless it chooses a class-based approach like that used for 
std::decimal::decimal128.

-- 
Joseph S. Myers
joseph@codesourcery.com