DRC is great move. Now bring Ethiopia on board - and we will have really big market. Somalia is a mess but if they apply why not.
They already applied a long time ago, along with Sudan. I think Sudan was vetoed by S. Sudan and Uganda, but I don't know why they've ignored Somalia. Maybe they're waiting for them to stabilize first. It's been years now since they applied. EAC haven't said a flat-out No, but hasn't progressed the discussion further. In conrast, TZ invited DRC to apply (Maghufuli) and they did in 2019. Just two years later, it's virtually complete now, only waiting for final touches.
Ethiopia has never applied but I've been reading countries have started eyeing EAC/EAF far more keenly now, and more might apply. So maybe Ethiopia will, plus a few more further South, like Mozambique which already speaks Swahili (but I don't know, just guessing they will after DRC, but I haven't studied their geopolitics so I don't know if this is even something they'd be interested in.)
I just hope the Horn is brought in, plus Mozambique, after DRC, and that harmonization and integration really kicks off. An entity like this could catapult development like dynamite. But even without the Horn, EAF would still achieve first world status if politicians don't ruin it with our usual baafrika nonsense.