Maybe not shifting, but adding. Alternative energy sources are being adopted in increasing ways, but in absolute numbers traditional sources keep increasing too.
Because we're talking about electricity the total power usage for the US is mostly stable.
It's not declining like the UK (efficiencies mean total electricity production is down about 25% this century despite population growth) but it's growing only a tiny fraction, like maybe 2% in a decade - much less than the amount of new solar and wind.
So it's definitely shifting, the biggest shift is away from coal. Coal is awful, it's too expensive and it's incredibly polluting, some of that shift is towards gas, which is also a fossil fuel but has the advantage that it burns cleaner and is often cheaper - but as we see in this data lots of the shift is to "green" sources.
No, it's definitely shifting, based on [0] the carbon emissions per kwh globally are down from 542 g/kwh to 481 g/kwh in the last 10 years, that's over a 10% reduction. Countries that are staying flat are the exception, not the norm.