I think the parties probably just touched on future merger options, while trying to sort out the current impact of the Lucasarts buyout. If it does go ahead, I think we could see major changes, as Disney would need to prioritise the greatest return to their core brand, over a subsidiary brand.
Even if this went ahead, it wouldn't occur too soon.

Future Movies - quality shouldn't be worse. Probably be better, as we saw how well Avengers turned out, under the ownership of Disney. Imagine that sort of action and plot-integrity with a TFs movie.

Toys - some elements will be better if they dictate the assortments, but ultimately the toys would be scaled back as Disney would be more invested in the multimedia elements, with toys being mere merchandise on the side. The toylines would be less extensive, as would the engineering, to match the younger Disney demographic. TakaraTomy would be an unknown element, as the Japanese like cutesy stuff, but also has a more dedicated collector demographic... so TT could obtain some independence to continue producing their own products, like they do at the moment.
Exclusives would also be less frequent under the "mere merchandise" model, and we'd probably see a lot more Disney-store exclusives (and crossover toys with their characters - which could see the JP ones being immediately re-released in American Disney stores).
And remember what happened when Hasbro bought out Kenner. Just like most take-overs, cost-cutting comes from consolidating or absorbing resources. If Disney ever did buy out Hasbro, there would be major consolidation with where-ever Disney creates their toys, possibly seeing the eventual closing of the Hasbro offices in Rhode Island (which is on the other side of the country to Disney offices in California).

Cartoons - Disney is more likely to absorb the HUB channel, using any shows that fit in its brand demographic. That would mean an end to TFPrime, like it did with Animated (which was axed to make way for a brand new show for the brand new HUB channel).

Comics - Consolidation (cost cutting) would naturally see all Hasbro IPs going to Disney's Marvel, prompting resets/relaunches, like IDW did when they got the TFs license.

Other Merchandising - We'd finally get a proper range of licensed merchandising, as Hasbro's prohibitive licensing structure (that prevents companies from taking the expensive risk) would be handled directly by Disney... and we see from their stores (and in regular department stores) that you can get just about anything with a Disney character plastered over it. Just not sure how much Adult merchandise Disney does though.

Collector Club - hehehe.... dare I give my thoughts/hopes on what happens there.


So many elements that would go in our favour, and against... if it were to ever happen, we're just going to have to adapt as a fandom. And worse case scenario, we have 28 years of Transformers toys, story and history to fall back on.