Should modern Christians keep the Sabbath? Yes. Is it possible? Not always. There are corporations that keep the Sabbath, but we all don't work at Hobby Lobby or Chick-fila. Most people do not work on Sundays, but they are not able to rest and take time for reflection and meditation. Our society is becoming more and more hustle and bustle.
Because it is Gods day and the 4 commandment says remember the Sabbath day to keep it holy, also the Sabbath day isn't on Sunday it is on Saturday because when Jesus died on the cross on Friday and one of Jesus' friend took him down fro the cross to bury him it was a custom to oil the body but because it was Friday sunset the time Sabbath comes in, they left the body in the tomb for Sunday which shows that the Sabbath is on Saturday (you can read these stories in all 4 gospels).
Yes, Christians should keep it, but most do not. We can worship any day of the week we want. But our Creator asked we keep the Sabbath the way HE commands. Friday night at sunset until Saturday night at sunset, a 24 hour date with our Creator that will bless you if you obey and keep it. There is no place in scripture that you can find Sabbath was ever changed to Sunday.
The Sabbath say (seventh day), was established immediately after creation in Eden (Genesis 2:1-3). Adam and Eve were not Jews.
In Exodus, God reaffirmed the Sabbath day with all of Israel, once again not the Jews. He was clear that the same law applies to both the alien and the Hebrew (Numbers 15:15). Jews come from the tribe of Judah, only one of Israel's twelve tribes.
Jesus did not annul the Sabbath. Rather, he said it was lawful to do good on the Sabbath (Matthew 12:12).
For years, society has been in decline. People have ventured further and further away from religion, and so people need to start respecting the Sabbath day again by not doing anything except going to church and spending time with their families on the Sabbath day. That way, society will be restored.