Another rumour being claimed is that there could be some reissue Transmetal Beast Wars toys (from back 1998).

This one feels like a bit of a stretch to me. Even though there have been a small number of reissues of 1980s toys, I don't think the toys of the late 1990s (Beast Era) have been used by Hasbro since the early 2000s of Armada and Universe. (TakaraTomy have recently reissued 2000 Beast Machines Air Attack Primal and 1999 Big Convoy)
The most recent use by Hasbro of a toy from close to that era (that I can think of) is the 2000 RID Megatron toy used for BotCon 2016 as Transmetal Megatron.

Going back further...
2014 - FunPub was able to use the Japanese 1998 BWII Dirgegun toy for Thrustinator. (the same year as Transmetals from Hasbro... but 7 years ago)
2013 - FunPub used the Japanese 1999 BWNeo Big Convoy toy for Ultra Mammoth)

2005 - BotCon used the 1998 Fuzor Buzzclaw mould... which I think could be the last time Hasbro used a "Beast Wars" mould. It was only 7 years after it was a regular retail toy by Hasbro, so could have been easier to track down... but I get the feeling that the Hasbro Beast Wars years of moulds (1996 to 1999) are off-limits, and remind me if I'm missing something, but in the last 16 years, that one Fuzor mould was the only Hasbro Beast Wars toy re-used by Hasbro, which to me seems a little unusual (if true).