Agree with what BBTC says above. Some of those with offers must be thinking they can do better elsewhere either financially or in terms of career development, otherwise why not sign up and go off and enjoy the summer break?
From how Palios' remarks were reported, there appeared to be an assumption that the players we'd made offers to would by and large remain. To my mind, there's merit in an assume nothing approach. I got the feeling wrong assumptions were made about Danny Holmes last season, for example. MP suggested we'd only need to bring 5 players in, but given Riley and Hogan gone, even if Ihiekwe and Gumbs sign their deals we still need at least another central defender. If they don't, significant re-building at the back.
My fear is a re-run of last year, where we hadn't got a balanced squad by the pre-season and we ended up using the friendlies to sling trialists together in the hope that something might click. Gateshead have shown that it's possible to recruit decent players at this point in the year. Perhaps enforcing a firm cut-off point around mid-June, by which point those who haven't re-signed can be moved on and replacements recruited for pre-season.