Why? Money! College presidents will seek it w/o regard for rivalries, coaches, athletes, fans. Most of the 30+ conferences & 347 D-1 teams are not currently competitive, might fare better after realignment.
How? One example: Eight 16-team, 2-division conferences, roughly geographic to control costs; 22 conference games: home & home w/in division, play each team in other division. At least 4 open dates spaced throughout season for OOC games.
Additional games (6?, 8?) pre- or post season for warm-ups, or conference tournaments (not necessary after 22 games -- oh, that's right, $).
After a 3 years, annual replacement of x number of under-performing teams by high-performing teams not in the 128.
Finally, no more than 64 teams make national tourney. Do I hear 48? 32?
Something like this is inevitable. Maybe decision-makers will consider your suggestions.