You need to be more specific when you simply say “nerf vortex.”
“Vortex” is a blanket statement that covers a number of mix-up options, all of which aren’t exactly unique to Akuma, although he certainly has more to bring to the table than many characters.
If for example his sweep gains extended recovery, it would cut some setups down. Likewise for extended recovery on his flip grab and also palm. If this were the case and his mix-ups were cut into in such a way, I’d perhaps prefer they relegated him to a damage and stun centric character ala vanilla. Akuma’s oki game exploitation was largely motivated by Capcom cutting into his damage and stun output, which forced us to get dirty to actually deal damage that otherwise came from creative attacking and solid punishing.
A 90 dmg lk tatsu and 160 dmg + 200 stun redball might be an interesting place to start along with sweep (i.e. from lk tatsu) dealing 110 dmg and 150 stun along with fs.hk being a viable option to FADC into after a fireball again. These ideas on paper are absurd, though they are on the assumption his Super/AE/2012 mixup game takes a serious hit and are on the onus he spends a good deal of meter to achieve maximised damage. I guess in a sense he’d return to an explosive damage + stun character somewhat below Evil Ryu albeit with perhaps better mobility.
Its hard to speculate though. I prefer the wait and see approach as its completely unknown as to how Capcom intend to change him, if at all. The character will always remain ‘good’ though I think the biggest fear I have personally is that his changes may well render him sluggish in some way. Once the feel of a character is meddled with in this sense it is very frustrating, particularly for those of us who have been using him since vanilla dropped.
We may well see a change to how Capcom handle hard knock-downs also. One idea many have tossed around is the idea of burning a stock to perform some kind of evasive quick-rise from a UTK. While somewhat “un-Street Fighter” it would assist many characters who have fickle or outright non-existent options on knock-down which in itself is a ‘nerf’ to Akuma and indeed any character who enjoys a bit of exploitative wake-up fuckery which has become a huge component of SFIV’s meta game.