Valve won't be releasing a Steam Deck with more performance until at least 2025. Given the smartphone market's reputation for disappointing incremental updates, this is the right choice. Valve should, however, throw gamers a bone with a Steam Deck 1.5.
They can offer a better screen without changing resolution. Better color accuracy, VRR, and maybe OLED would improve the screen without changing the performance target.
You can improve the screen without impacting performance. Larger screen, smaller bezels, better colors, OLED, matte finish (on cheaper models), better touch accuracy, etc.