What's the upload speed in this example? Symmetric 100Mb would be more than fine for 4 people. And just fine with 100/25. However, 100/5 will be stressful.
DOCSIS 4.0 was ( finally ) finalised last year. And could be pushed for upgrading. But that is just the last mile, Cable companies will still have to ensure fibre roll out. Look at UK. They had a half decent infrastructure with DSL and could have pushed G.Fast, instead they just bite the bullet and pushed FTTP to maximum.