I can only give my opinion and its probably not worth the usual 2 cents!
There are four things that stand out in John 6; faith, bread, flesh and eternal life and all four of these things are all connected to one another. We must have faith and believe that Jesus is who or what he says He is…the Bread of Life, we must also believe that this Bread is His flesh and that by eating His flesh (Bread of Life) we will live forever! If we do not believe these things and do not eat His flesh then we do not recieve eternal life!
This is why the Church tells us that we must recieve the Eucharist at least once a year. Those that were present heard this teaching straight from Jesus’ mouth, those that came after heard it from His Church and those who are separated from His Church do not hear it at all. I do not believe all non Catholics are going to hell because they dont receive the Eucharist, most of them especially today will hopefully be covered by invincible ignorance.
But Jesus’ message is quite clear, by eating His flesh we receive Him who is the Bread of Life; He abides in us and we in Him and just as His body rose to heaven, He in turn will raise our bodies on the last day! After all when we receive Communion we united with His body and His body includes all the faithful so it only makes sense that where His body goes so will the mystical body.