It's really hard already to know what was the state of PIE after Indo-Hittite differentiation and when this differenciation happened : assuming a Chalcolitic migration of proto-Anatolians, and that the pre-IE languages substrate weren't formative in the constitution of other branches of IE (at least in Europe)*, it doesn't let much certainties (outside the glottochronological method, which I find dubious at best).
I'd still be tempted to say this PIE evolution would be more conservative and closer to Anatolian language than how it did, partially due to its lack of variety, partially due to its closeness to Anatolia, but to eventually be more vulnerable to linguistical influence from other regions, demographically-wise. But that's pure unsupported broad opinion.
*I'm personally unsure for the former, slightly more trusting in the latter.