Impossible. If they include the Tiefling but not the Gnome, they will anger one side; if they include the Gnome but not the Tiefling, they will anger the other. The only way to satisfy both camps would seem be to include all the previously-core races: Human, Dragonborn, Dwarf, Elf, Gnome, Half-elf, Half-orc, Halfling and Tiefling.
But even the all-inclusive model won't work. The Dragonborn, in particular, have some very vocal fans, but there is also a very vocal group who very definitely don't want them included in the core.
If the 'big 4' are indeed so overwhelmingly popular (which I'm honestly not certain I believe, but don't have any actual reason to doubt), then perhaps the way forward is to include only those in the core, and make everything else an option.
Fair enough, but if each race takes up a 2-page spread (as in 4e), then for each race you include you're going to have to cut something substantial to make room. Is your desire for races that you rarely use (or, worse, ones you're going to houserule out of your game) really so great that you're willing to lose, say, magic items from the core entirely?