You're thinking in the past. Campaigning doesn't even require the physical presence of the candidate anymore. Trump loved his rallies but he actually did fewer in-person events than most candidates and still won.
All the movement is in social media, traditional media, and targeted ad buys on one end, and get-out-the-vote efforts and massive ground engagement on the other end. The physical presence of the candidate at rallies is mostly a sideshow.
On top of that, plenty of swing states (Florida, Virginia, North Carolina, Pennsylvania, Ohio, Michigan, and soon to be Texas) are big enough that presidents will still campaign there themselves even with a popular vote. Iowa, New Hampshire, and Nevada will still get tons of focus because they come early in the primary calendar. So who is losing out, New Mexico?
Better than the current system, where every state with a big enough margin is ignored completely. Without the electoral college the candidates will have an incentive to grab every vote they can in EVERY state.