FUE 2000 grafts with depleted donor area. Is this fixable? Future hair transplant possible? (Photo)

This is an example of poor donor management. 2000 grafts should of been extracted over the entire donor area, and not focused on the patch shown in the photo. Unfortunately, now that the grafts have been harvested, the only way to remedy this problem is to harvest grafts from outside the patch and place them in the patch to restore density. The other option is to have SMP into the donor area to increase the illusion of density.

Your donor area will always look "thinner" proportionate to the number of hairs taken out after a FUE harvesting surgery.  The hairs will NOT grow back from the donor area (where it was taken). If it all goes to plan the donor hairs will grow in the area it was transplanted.If you are concerned about your donor area, you need an examination and the doctor needs to understand your goals and expectations.

you can get future transplant done from the remaining donor area from scalp and from other non scalp areas like beard and chest hair.
the over harvested donor area can either be managed by camouflage procedures like keeping long hair, scalp micropigmentation, or extracting other areas to create even look

It could be a shock loss at donor site, Its too early to judge the things in just 2 months. In most of the cases shock loss is recovered in 5-6 months. 
They tried to extract maximum grafts targeting a small area causes an uneven density & a visible over-harvested patchy area. 
The short term solution is to keep your hair long to cover the patch or go for SMP & whenever you are planning for next session, opt FUT or the combine technique of FUT + FUE. Around 2 more FUT sittings can be expected with the available donor area and eventually FUE session may be needed for scar repair with a small number of grafts 

You should find a doctor who can perform SMP on the donor area and to finish up your hair transplant with the strip method of harvesting.