Your quote "Are the stones and the woods of the Ka'ba themselves holy, sacred or important? No, but the objective is important and not the means. So, we (will) should focus on the exact mechanism of Kaba for unifying of the human being and we must implement its concept on a conventioned planet in a conventioned place at that time (i.e. when there is no habitable earth)."
Answer; the object of the Kaaba should be to unify mankind with VALUES, PRINCIPLES, UNIVERSAL LAWS, etc not make the site holy and important but the objectives as to why it was chosen.
WHEN human beings go off planet, they will still need a command centre, a council hall, a parliament so they will choose one for themselves where they are.; I will leave it to Luke Skywalker to work out the details, not Darth Vader.
Your quote "However, today, we should continue our true (and not traditional-ritualistic) Hajj and accept the physical Kaaba as our symbol and focal point of Deen and take the HAJJ and KA'BA verses as literal-metaphorical and not absolutely metaphorical (and ignoring physical Kaaba)."
Answer, until the demise of the earth we will have to unify mankind with a global centre and i see no reason why Kaaba will not be used one day for this. Until then, those who know right from wrong should not indulge the mullas and the five star hotel/package holiday holy hajj and umrah capitalists and not do this pagan ritual. I am waiting for them to announce they have found a new hadith that men can walk around the kaaba once more naked, just like the good old days as they have done most of everything else they used to do!