If construction on the Master Planned Development, and specifically the center you reference, has not begun then do not close on the property.
Since it sounds like you've already negotiated price and terms, you'll need to attempt to renegotiate the closing terms, and if possible the conditions present to trigger a closing.
If your use of the land is dependent upon the performance of the master developer completing X, Y & Z before you can freely and readily utilize your land then X, Y & Z should be a condition precedent to trigger your close of escrow.
As the buyer in a master planned development, you want your PSA with a reasonable deposit to act as an option to purchase that is conditioned on future events being met. You will have the condition to close if the terms of the PSA are met by the seller, and then also have the option to cancel the PSA if they are not. The Seller has performance conditions they need to meet to trigger the closing. They do not have the option of canceling the PSA.
Many Master Planned developments sit vacant and unbuilt by developers who have great plans but not the resources, or access to the resources, that are required to begin, sustain, or complete the development. When discussing master planned developments its important to keep in ming every service and societal benefit we all normally take for granted, streets, lights, gas, water, toilets, rain runoff, etc., must be 'built' into the master planned development. Any master planned development is a huge commitment for its developer.
The only exception would be if the developer was a local 'billionaire' type developer operating a gigantic development organization.
My suggestion is you seek out the assistance of a good real estate attorney to help you draft or alter the PSA to include terms that help you reduce monetary loss and your development position.
Avoid letting easy or convenient sale terms dictate your decision. After all, a great 'deal' where you can lose all your capital will never be a good deal. Risk mitigation is more important, particularly in cases such as this where so much is dependent upon an others performance.