The mark of the beast will cause a great falling away of many of the saints of God as they believed a lie that they would be caught up to Christ before the seven trumpets of God's great wrath being poured out into the world that will cause great tribulations. The seventh trumpet will usher in the timing of the son of perdition who takes his literal seat in Jerusalem on the very temple mount of God. He will demand allegiance of the people throughout every nation on every continent as he deceives the nations showing he is God by using lying signs and wonders, promising peace, safety and provision to all who will bow down and worship him, 2 Thessalonians 2:1-12.
IMO, I believe this mark of the beast is that of the thoughts of the mind and the actions of the hands as many will believe he is God and will reach out and accept him as God. As far as chip implants and the change in currency in order to buy and sell, I can see this happening, but yet we are told in scripture to not accept any of it.