He won't be able to do much (except executive actions) for first 2 years but if your country can go through the same change we just did, you can elect a democrat congress!
Democrats don't have a chance in hell at taking the House any time before the 2020 Census can rewrite the demographics in certain states at the absolute earliest (meaning the 2022 election). And that's probably the best case scenario. Shit's too gerrymandered to do much about the entrenched Republicans.