Forget about the races for now. Here's three
archetypes I would like to keep:
1) Friendly, nature loving fey. This is the archetypes closest to the mythological gnomes (some shades of Tolkien's Hobbits as well, actually). I would much rather see these guys as *actual* fey with magical abilities, rather than some but otherwise very human-like race.
2) Tinkers. No particularly strong reason why they should be Small, although their size does somewhat restrict the spread of technological gadgets, and when things eventually do blow up, the explosion might be proportionally smaller.
3) Sticky-fingered pranksters. This archetype seems to have been adopted for Halflings in 3.X, although this is very far from their original Hobbit roots.
None of these include illusionist Wizards with pint-sized spellbooks, or traveling bards (although "traveling bard" might be a good day job for a sticky-fingered prankster).
As long as these archetypes remain available, I don't particularly care if gnomes and/or halflings are removed. But if Gnomes stay, I would greatly prefer if they were returned to their mythological roots or small magical fey. And if Halflings stay, they should probably be returned to their roots of jovial, rotund and somewhat reclusive Hobbits...