Thanks for the replies.
I guess that any issues that arise regarding permanence probably relate more to the means and quality of storage, rather than what (in this case TIFFs) is being stored.
There is quite a lot out there on what is termed "bit rot", this being but one example. https://madfileformatscience.garymcgath.com/2016/05/19/uncompressed/
I'm wondering if there are some types of file that are less susceptible to bit rot than others? e.g. For a photographer, should one be storing RAW or DNG files rather than TIFFs? (This approach would have two added advantages - 1. Space: a RAW file is about 1/6 the size of a 16bit TIFF. 2. Software: A RAW file captured in, say, 2011, is still that RAW file. But, a TIFF produced from it on 2017 RAW processing software is almost invariably an improvement.)
Food for thought.