I feel like this change takes her away from the support role and places her in the mage role (a machine gun mage) like Ryze (I'll get to that in a second). Here's my breakdown:
Her new R when stacked with 40% CDR gives 52/58/64% which now changes your Q from 8s (0 cdr) or 4.8s (40% cdr) to 3.84/3.36/2.88s (52/58/64% respectively) and while they did lower her damage by 40 points at max rank, you could almost get 2 Q's off compared to pre-change (well, almost: 5.76s vs 4.8s). While this does increase her overall damage the longer she stays in a teamfight, she gets a much larger benefit by building full AP compared to building support. 500 AP with a .5 ratio and 2 Q's fired off instead of the normal 1 is quite powerful (especially if you add in Lich Bane) This also has the same CDR on her E (8s base, 3.84/3.36/2.88s with max CDR + R passive) and make's her W from 10s (0 cdr) or 6s (40% cdr) to 4.8/4.2/3.6s (52/58/64% respectively). Her R get's a huge buff as well (at max CDR it makes it 36s at rank 3).
Now it is true she only has 4 forms of damage (her Q, her passive, her secondary damage on Q + Lich Bane autos, and her R) it doesn't quite make her on the same level as Ryze. It does, however, allow her to spam her spells just like him. Which also brings up the first major issue with this change as a support character: mana costs. While it will be pretty cool to spam Q every 2.88 seconds (while autoing with Lich Bane) your mana pool will be gone faster then the enemy can kill you. Her base mana is 1106 at level 18 (according to the wiki) and each Q is 65 mana. A full rotation (Q+E+Q) will be 195 mana, add 100 more if you need to throw in a W. While Lich Bane does give 250 mana, you would still need to rely on more mana items and/or blue buff (which I would want on my Mid, not on my support. Unless of course you have a mid and jungle who are manaless/resourceless then by all means).
Another issue with this change is it lowers her early game damage as a support (and a Mid as well), while increasing her late game damage (by a lot for Mid). While she will get to around 40% CDR near mid and late game (depending on your build + runes + masteries) as a support she loses the early game damage and will just become a walking speed buff + healbot until she can pick up a little AP + Lich Bane (and we all know how gold starved supports are compared to the rest of the roles) and at that point her damage gets mitigated by MR (thanks tank meta). She also won't have that 64% cooldown until she hit's level 16 (which is pretty late game for a support). For her role as a Mid laner, while on paper she looks pretty strong with the changes, her early game will be pretty sad. Until she gets a decent amount of AP + Lich Bane her damage in lane will be quite low. She can't clear fast, most of her damage will come from Q + passive (and any mid laner will just build MR to shut her down), and she is pretty squishy with no strong escapes (her MS is nice, but doesn't compare to a dash or a blink). On the flip side, with 500 AP and Lich Bane you can Q + Auto + E + Auto + Q + Auto (proc passive) to deal 410 (160 + 250 (.5 ap ratio)) + 586.75 (101 base damage at level 18 + Lich Bane Proc of 325.75 + 160 from Q auto attack damage increase) + 426.75 (E does no damage, but will reproc Lich Bane) + 410 (Q) + 995.55 (268.8 max level passive + 140 on the AP ratio due to Q passive damage increase + 160 from Q damage increase on next auto + 426.75 from Lich Bane Proc and base damage at level 18) for a grand total of 2,829.05 damage in about 6-7 seconds with E will also help you get out of range so you can get ready to do it again. Please take the theory craft above with a grain of salt, as it looks strong in theory, you might not get to output that damage in a team fight, especially when everyone is trying to focus you and/or ADC.
I could go on, but all in all do I feel like this would make her a stronger support overall? Yes. While she does get some nerfs to her early game, her late game becomes quite strong (even without 500 AP). However on the flipside if these changes go through do I think she will become one of the strongest late game supports? Yes. And the downside to having someone who can spam a heal every 3.6 seconds giving 196 heals (not including AP, but including the 30% heals and shields buff from the 2 items + 10% from masteries) and 182 shields will make her either first pick or banned every game. Even if she is weaker at the higher ELO, the lower ELO will be destroyed by her which will lead to more nerfs :(
So while I think this will be a strong change for her, I feel like it will hurt her overall in the long run.
Also I don't know if anything else in her kit changed so I apologize if any of my numbers above are wrong.