I am not too familiar with the technical jargon, so bear with me while I explain the issue in simple and naive words. I have looked into many places but still haven't found a solution to this specific problem. (such as this, or this, etc.)
A bit of (un-)related background:
I have recently come across several articles that outline the unparalleled prowess of GPUs in cracking passwords.
One such article was the use of a 25-GPU cluster to crack any Windows password in about six hours. Another article here claims that one Nvidia GTX 1080 can be 250 times faster than a powerful Intel CPU in cracking passwords.
It is also worth mentioning that a standard crypto-mining farm owns about 500-1000 GPUs.
My question here is twofold, but mainly concerns the endurance of passwords/encryption methods we use right now against future breaks/cracks.
Suppose I send an archive of confidential information to a friend over the Internet (using Google Drive, Torrent, Dropbox, or whatever) and this archive is encrypted using a tool such as VeraCrypt with the three-Cipher cascade of algorithms (e.g. RSA(Serpent(Two-fish))) and a password that is 64 characters in length and contains lowercase, uppercase, numbers, symbols, and has a very high entropy. Now, a very keen hacker gets their hands on the file during the transfer and stores the file "forever", i.e. until they are able to break into it. Probably, they will share the file with their other hacker friends and collectively spread it to many other hackers to work on it.. The assumption is that my file is now spread among many people who are going to retain it until the day they can break into it.
Getting back to the questions; First, I want to understand the relation between time, computing power/resources, and breaking a certain encryption algorithm. How can we become immune to the future? Given that our file is now in the hands of a dozen of hackers who are stubborn enough to store it for many, many decades, how can we estimate when they are going to break into it, taking into account the three encryption algorithms and the strong password we have used and the gradual technological advances (e.g. average improvement in hash rate per year/decade, faster CPUs and GPUs, decrease in price and more people getting their hands on more powerful resources, etc.).
Second, would the results (time and computing power needed) change if we add keyfiles to our encryption process? Will the number become bigger if we add more keyfiles?