Al-Isfahani is relatively hard for GDI to get at- we're in no position to stage offensives out of BZ-18. India, likewise; the only lines of attack are amphibious and we had our hands full.
I hope, mind you, that Nod's intelligence on our top-level decision-making wasn't so wide-open that they specifically expect Karachi. Though they can read a map and know we must be tempted to try something like that.
I doubt they knew/know to expect Eastern Paris specifically, but like you say, they can read a map. If I was NOD India, I'd be very concerned about the region between Miani Hor and the Gulf of Kutch. That is the region closest to GDI presence in Oman. The other potential target point would be Sri Lanka, but I'd be less concerned about that thanks to the relative proximity of Bintang's stomping grounds to the east. But those two places would be where I'd expect an amphibious invasion.
I might focus more on Sri Lanka, just because it would be more difficult to get supplies there if GDI attacked in force, but I'd prepare defenses in both locations.
The wild third option is an attack down from the Tibetian Plateau, which is something I would not be expecting at all because of how crazy the logistics issues the GDI would suffer supporting an offensive from that direction. If/when the GDI completes suborbital shuttles and OSRCT, I'd be more concerned about an attack from that direction, but until that point, my big concern is a naval invasion.
But moving back to the coastline from Miani Hor to the Gulf of Kutch, determining exactly where the GDI would choose to land is difficult, because it depends on the underlying motives of the GDI. If the GDI wanted to get a FOB as close to NOD India's heartland as possible for raiding or disruption attacks, while still being supported by BZ-4 the landing zone would favor the Gulf of Kutch, likely targeting Jamnagar. If they wanted a base to attack Red Zone 3 as part of their counter Tiberium efforts they'd favor Miani Hor potentially going as far west as Kund Malir and the Hingol River. Where such a base would be more for defense for future GDI Red Zone Glacier Mines then to act as a FOB. Then there is the Indus River if the focus is to reach North and link up with BZ-18.
Or it could be a combination of those goals. Karachi and area between the Hub and Malir Rivers makes an excellent target if the goal is both BZ-18 and Tiberium Mitigation, it is right on the border with RZ-3 and perfectly positioned to project influence over the mouth of the Indus, even though its a lot further north of the mouth of the river itself. The coastline of the Kutch district is a good target for a balance between relieving BZ-18 and attacking NOD India's heartland.
As Nod India I'd be most concerned about a potential attack against my home infrastructure and factories. Specifically I'd be very worried about how vulnerable Mumbai is on the western coast of India directly across the Arabian Sea from Oman. It is what I'd have nightmares about waking up too, a GDI amphibious invasion of the second largest city in India, and one of the top contenders for my center of power. The other being Delhi which is pretty close to BZ-18 and as a result I might want to keep my capital away from that potential threat, plus with the mouth of the Ganges terminating in a Red Zone Glacier, Delhi might have dwindled in importance comparatively.
In any event I, as NOD India, would be extremely worried about a Bintang Tokyo raid style attack on Mumbai by the GDI. Something not intending to take territory, just intending to do as much damage as possible. Something similar to our first attack on Jacksonville in our fight against Gideon. That is where I must focus my coastal defensive efforts, because losing Mumbai would probably be devastating. This is not to say I wouldn't have defenses further north from Karachi to Surat (and south in and around Sri Lanka), but my worst case scenario would be a direct attack on Mumbai.
A long winded way of saying, as NOD India, unless I had very accurate intel on exactly where the GDI was planning to attack I'd have to focus my defensive efforts where it would hurt the most if they hit. And that place is most likely Mumbai, not Karachi, or wherever I think the GDI is more likely to attack. Simply because I couldn't take the risk.
