Valor upgrading is not for "I just got this item and it's better, so I need to upgrade it to make it better.... er", it's more along the lines of "I'm not replacing this item in the foreseeable future so I'm going to make it even more non-replaceable".
You may gem, enchant and/or reforge a "temporary" item until your preferred item drops, but since it's going to be highly unlikely you'll earn enough valor to upgrade every slot that has an item, and more than once each slotted item, upgrading, as an example, an LFR item when you're in a guild running normal and/or heroic content is essentially a waste of valor that you can't recoup. Besides, even if you were to upgrade the LFR item, the ilvl upgrade from an LFR item that is upgraded compared to a normal mode drop (and this difference is even greater for heroic items) is enough to replace the item before upgrading unless the secondary stats are inferior, in which case it probably wouldn't be an item you'd wish to spend valor on upgrading it anyhow.
What puzzles me most about what's been announced is why the "old" valor items are not being moved down to justice points purchases. With as valuable as valor is, it's hard to believe that spending 625 valor on a 489 ring is a wise purchase instead of spending 1250 on a 508 ring (and that's just an estimate of 19 ilvl upgrade as was the case of tier 9 to tier 10 as well as tier 11 to 12 and from there to 13). And with honor gear being available at 476 item level, does PvP become the preferred method to level a new 90 post 5.2? Or perhaps with the justice point increase from bosses it moves to farming bosses in heroics to convert to honor to buy gear, but that was kind of how it worked at release when justice gear was 450 and honor gear was 464, and they ended up buffing justice gear slightly and dropping item level on honor gear a little bit so that people didn't feel they "had" to PvP to gear efficiently for PvE. However, doesn't it seem that it may go that route again?