I disagree that after the church( His body, His Bride) is removed from this Earth, the dispensation of Grace will disappear. For as in the beginning, it is by the Grace of God that mankind is still here. Abraham never formally knew what the laws of Moses were. By the Grace of God is the only thing that salvation comes from. The 'Everlasting Gospel' will be the law from the time after the Rapture to the time of Eternity which includes the millennium to come. During this time, there will be multitudes of those that show their faith in Jesus by losing their heads (literally). For after the Pre-Trib Rapture event happens and it will happen, there will be for a short period of time, no one left on earth above ground or below ground that believes in Jesus Christ..Those that die during this period of time, formally know as the 'tribulation' saints are brought on by the 144,000 Jewish ministers, the Angel (carrying the Everlasting Gospel) and the two witnesses all sent to earth to preach the Everlasting Gospel to those that would come to believe in Jesus Christ during Daniel''s 70th week.
The law is undergirded by grace, but that doesn't mean that only grace will save under the law. You still have to keep the law under the law.