Following SegWit implementation, is BIP-146 signalling and implementation still on the docket?
Bitcoin-core already enforces low S-values as a standardness rule for transaction relay, but making a transaction non-standard does not cause a softfork. 

BIP-146 does call for a softfork by making high S-values in tx signatures invalid, not just nonstandard. 

The BIP also states that the majority of txs on the network already adhere to the low S rule, as of Aug 2016. To quote from it:


  The reference client has produced LOW_S compatible signatures since v0.9.0, and the LOW_S rule has been enforced as relay policy by the reference client since v0.11.1. As of August 2016, very few transactions violating the requirement are being added to the chain. For all scriptPubKey types in actual use, non-compliant signatures can trivially be converted into compliant ones, so there is no loss of functionality by these requirements.