Hotels in Osaka & Kyoto for 2015 Sakura

Is it too late now to be booking hotels in Osaka and Kyoto for the Sakura season?

probably, most of famous and convenient hotels are already full.
you may look for hotels around:
1. between Kyoto and Osaka
2. between Osaka, Kobe, and Akashi
3. between Osaka and KIX
4. between Osaka and Nara.

Sakura is everywhere in Japan. locals enjoy Sakura nearby of their places (not go to crowded places).

Not necessarily, but you'll have to really get on it and be patient. Some advice here: http://www.japan-guide.com/news/0029.html I recommend, especially the "stay nearby" portion.

Also, people do cancel. I suggest trying Toyoko Inns around the area and just refreshing the page every once in awhile; you might get lucky! Same goes for other hotels.

For a good hotel, hope for a cancellation. Otherwise you will probably find availability at the top end or bottom end places.

Have you thought about Nagoya? It's not that far/long by train.