Neymar can never be a good option for a team like Dortmund and I'm sure they know this player is far from his good form and he can't have good performance anymore. Also as far as I know Dortmund usually prefers to use the younger talents in the team instead of buying expensive and older players like Neymar.
Neymar is a superb soccer player but given Borussia Dortmund transfer policy and financial limitations, it appears doubtful that they will try to sign him as a winger. Dortmund is renowned for developing young players and emphasising team building over acquiring expensive big stars. Neymar expensive salary demands and injury history may further discourage European teams from giving him any consideration. Given his availability and potential fit with the team plan, Serge Gnabry might be a more practical target for Dortmund if they are in the market for a winger. Given the financial considerations, any prospective deal for Neymar this summer might be restricted to Saudi teams.