Broken glass can be repaired within hours, same for cleaning up and laying a temporary carpet.
IMO most of the damage is superficial, so it will probably be taken care of in a matter of a couple of days and then repaired professionally later on.
IF the structural integrity of the terminal building is ok.. otherwise....
That is indeed the big question...
Only after a extensive examination it can be determined if the terminal is structual sound something that is not sure at this point. Brussels departure had his advantages but also soms disadvantages. The biggest advantage is that it's a big wide open structure which allows the shockwave from a blast to spread and cause less damage contrary to a blast in an enclosed space, however the big downside is that the ceiling is low in the terminal which didn't allow the shockwave to disperse upwards, the complete shockwave thus had to disperse left/right/front/back while being blocked by a low ceiling and the floor. This happened not once but 3 times (DOVO opted to have the undetonated explosives detonated inside the terminal rather then take additional risks and move them to an open area). Such blasts can seriously damage the structure of a building with every blast worsening the structural soundness of the building. I'm not sure how the terminal was constructed back in the nineties, if they used a metal skeleton then the chances for severe structural damages seem limited, if they used a metal reinforced concrete skeleton the damage could be more severe. The biggest luck they had is that no severe fire broke out after the blasts since this would have further impacted the structure due the heat.
So the best possible scenario is that the structure is sound and passes the inspection. In that case it's indeed mostly superficial damage (though I think the schrapnel could also caused severe damage to electrical systems) and then it will be indeed days before the airport can be operational to some degree and gradually pick up pace later.
The worst case scenario is that the structure is compromised and then it will probably take weeks before the terminal can be opened for some activities (well actually that's not even the worst case scenario, the worst case scenario would be that the structure is compromised in such degree that normal repairs aren't possible and a demolition is warranted but I doubt this is the case, let's not think about that).
Honestly? I doubt BRU will be operational in the next couple of days, it might take indeed until after the weekend to get BRU operational to some degree.