There's still quite a bit not encrypted out there, and some services will never go encrypted (civilian air, for example). But quite a few have gone digital (digital is not equal to encrypted, but there can be encrypted digital), and the SDS100 excels in handling both conventional digital, trunked digital, as well as conventional analogue. It is not, by any means, perfect, but it does what it's supposed to, and quite well, in my opinion. Expensive, yes, but it's worth it.
As for just rail, many systems have gone digital, mostly DMR and NXDN, though some others, as well... The extra cost of buying these two upgrades practically make the SDS100 twice as useful. The waterfall upgrade isn't necessary, but it can be handy, and even add more time with the scanner. ProVoice? Officially, it's at end of life, but it's still being used, and might be worth having, "just in case".
I should know, as I have an SDS100, and although I live in a rural area, I'm quite happy with mine.