Fabrizio Romano always shares news from trusted sources and the accuracy rate reaches 100%, even though everything he shares on his personal social media is not always true, most of his news manages to come true. Kroos decision is final, he will retire as a professional player and Real Madrid will be the last club he plays for during his career as a footballer. Real Madrid has completed all the documents related to the signing of Mbappe, he has officially become a new Real Madrid player even though there has been no official announcement from the club.
Retiring from active football is usually the sole decision of a player especially when he aged or probably have become to injury prone that for health reasons he's forced to retire but then it's still very much dependent on the players decision especially when it's not on health grounds, so a player can say he will be retiring soon and for some reason go back from his words and not retire again.
Mbappes deal has been considered a done deal and probably ready for him to start training with the team so that by next season he will be playing for the team already, with Romano, deal confirmations usually have a almost 100% accuracy rate, so I literally nurse almost no doubt for this news as it's been long anticipated, for about two seasons there have been rumors around mbappe moving to Madrid so getting a new as this at this time sounds more like such that has been expected because it's been in the media for a long time about his possible move to Madrid.
Kroos on the other had have done a whole lot for Madrid all his stay at Madrid and even the fans and the management appears to love and still want him, of which I'm optimistic about the chances of him still sticking around in Madrid till there's a final decision on retirement form him, but in the means time, he's still very much accepted and welcomed in the team even with the presence of mabappe, they both wouldn't have a clash of position so I don't even see a challenge in that.