6 lanes, 25 m pool is not that huge, parcour will be smaller (9 obstacles, 12 jumps - one double, one triple), the piste is on the same stage as podium and the running course will be shorter (600 m) and the range will have 12 stands only (+reserve - probably two). The one in Budapest did not seem bigger than a football pitch.
The other thing is what do athletes say: "the end", "they killed the modern pentathlon", "the heart might stop", "did athletes have any vote on this ever?"... the decision is not final and luckily the IOC will gather in December, while the UIPM Congress to approve it will be next year, when the Paris 2024 spot will be sure. Some are however worried about LA 2028 - if we change the sport every four years, it's not spectator-friendly. Athletes (mostly Irish ones) insist on changing in marketing and TV coverage instead of such drastic changes in the format and accepting it (by EB, not finally yet, but...) after just two tests - one in Hungary, one in Egypt. Most of the world didn't have any chance to try it.