Yeah, I really hope Cap doesn't keep that shield too long. ESPECIALLY if they ended Infinity Wars with the classic Cap facing Thanos scene where his shield breaks. I agree that it's probably not going to be there the whole gilm... But it makes me uneasy that that's the only shield we see in any promotional media, or even the toys. I would think the toys would be based on the main outfit of the hero, and I think it seems like it would be weird for him to go back and change into his Cap suit just for the audience. I think he's going to be Nomad in this film. Maybe, best case scenario, he returns in full stars and stripes with his shield just for a closing scene where Thanos breaks his shield, and possibly even kills him. I don't see it as likely for him to return to stripes and stars, not until the next film, whether in memories/flashbacks/visions of him after he has possibly died, or his resurrection through infinity stones.
(Also, note, I've steered clear of any spoilers for the next 2 Avengers films, even though I've seen articles claiming that the cast of the next film reveals who lives or dies, I haven't seen set photos of either film which reveal anything like that. Basically, don't spoil anything for me, and everything I said was speculation.)