@AirborneAFOL already explained why you should not worry, and here are my two cents as well. I asked for the GG for my 42nd birthday from my father in law, since I didn't know what to ask. I always played with Lego since I was 7 year old and I still have my first two sets at home in the original box with instructions; all in good shape. I really liked building the GG and bought the next one. Thought about investing for the GG and never did, and look what a new one does nowadays; probably an easy $1000.00 if you have patience.
so the money investment is not a problem, that will sure come back if you sell them again, even used. Just make sure it's complete and not damaged at all. I kind of clear coat all my Lego sets; and got lots of compliments from buyers who buy my used sets, that they are in almost perfect shape. And it makes the boxes easy to clean as well.
I regret not buying the CC set, because I have them all, besides the last two. But I will get these too, just not in a hurry, because they won't retire that fast, you always have two to three years. Just got the Lego Porsche 42056, and that one is still taking my breath away.
My advise: don't hesitate to get these sets, because they will not depreciate in value. If Lego ever stops the line altogether, they will become worth even more...