1. No Samsara: no need to break this wheel, it never exists!!
On this view, you would have to claim that one must be convinced of the speculative metaphysics of rebirth before one could come to see that samsara is dukkha. However, "birth, old age, death, sorrow, lamentation, misery, grief, and despair
" can be observed as dukkha without recourse to such speculation, and as such the Four Noble Truths are not reliant on rebirth as their raison d'etre.
2. No 4 Fruits: ex: no Stream-Enterer (defined as: rebirth up to seven more times as a human or in a heaven); no Arhant (everyone would automatically become an "arhant" at the end of their life)
It's possible to be motivated by the idea of "seven lives or less remaining", but it is also possible to be motivated by "independent of others in the Dhamma" or perhaps "a pinch of sand's worth of suffering compared to the mountain of the putthujana" and so on. The list of qualities of these ariyan disciples have enough to offer the rebirth skeptic that rebirth is unnecessary here as well.
3. No 12 links of DO: Becoming (Bhava) was gone; Vinnana wouldn't give rise to Namarupa.
Well, suffice it to say that there are other exegetical iterations of paticcasamuppada that do not rely on rebirth at all.
4. Severely "waterdowned" Kamma: it couldn't be applied to the case of child prodigies or extreme mishaps to newborns; with past life and future life gone, Kamma's scope is down to 1/3: the present life only;You're born rich or poor, smart or dumb, beautiful or ugly, prestigious or low, ...all due to chance, not Kamma.
Kamma isn't the cause of everything, and saying it is misrepresents the Buddha's teaching on it.
5. No 4 NT: see Alex's detail description above.
Rebirth is found throughout the Suttas? Yes. Rebirth belief is necessary for practice? No.
The importance of rebirth is very much over-emphasized, and it does a disservice in the face of those who have only a little dust in their eyes, and would practice the Dhamma for great benefit but for this sort of metaphysics. If asked, one must respond that it is involved in the milieu of the Buddha and his teachings, but to claim that it is required for orthopraxis is false.