Can someone explain to me some aspects about the jungle changes?

The PBE changes indicate that the following will occur:

• Gromp and Wolves will spawn 15 seconds after other camps, thereby making obtaining a solid leash nearly impossible. Also, the inability to start on either far side of the jungle will force junglers into inefficient pathing.
• Smite bonuses are gone, thereby rendering decision-making in the jungle absolutely meaningless.
• Worst of all, camps will respawn every 150 seconds instead of every 100 seconds, thereby stifling gold and experience gain for junglers (both form their own and the enemy's jungle), and effectively nerfing (severely) junglers who thrive largely on fast clears.
• All told, junglers will be left with less options of things to do.

Will someone explain to me how this won't devastate both the power level of junglers (particulary the third item on the list, as it'll effectively mean 33% less gold and experience) and any strategy that goes into jungling?

Take Rumble, for example. One of the essential pillars of his viability is his fast clears, particularly after completion of Runic Echoes. I'm pretty sure that, at 10 minutes or so, he will find myself with long stretches during which there will be no jungle camps available to clear. This will hurt, very badly.

Another problem with the higher respawn timers: weak early game junglers will be at a tremendous disadvantage. Jungle invades will be FAR more impactful, as the loss of early camps----annoying right now, but not devastating----will become absolutely crippling. The opportunity cost of ganks will also increase tremendously; should the enemy jungler be on the opposite side of the map and do the sensible thing in clearing the enemy's jungle, the impact will be tremendously higher than it is now.

As a jungle main, I'm just tremendously concerned right now. Someone please give me reasons why everything will be OK.