Basing from Mark 16:15, what is the impact of not spreading the Gospel?

Mark 16:15 (2)

From all indications, it's obvious that Mark 16:9-20 is not original to the real Gospel. Those verses do not appear in the older manuscripts like Codex Sinaiticus and Codex Vaticanus.

Brother Elisoriano took it upon himself to visit the British Library where he found that those verses were not included in the English translation of Codex Sinaiticus - a Bible that is as old as 1,600 years.

We can see that both the church historian, Eusebius and Jerome had their suspicions about this portion of the Bible which scholars refer to as the "Longer ending of Mark".

Also, the use of the word, "creature" puts a question mark on authenticity of Mk. 16:15. This is because we cannot preach to every creature which we know includes animals. This is unlike Matthew 28:19 which says "...go ye unto all nations..." which implies talking to human beings.

Finally, the issue of going from house to house to preach (though not bad in itself) is surely an outdated pattern in the presence of modern means of communication like Internet, TV, Radio and Satellites.