The 'Messi Saga' still has a long way to go before it reaches a conclusion. For now, the player is adamant that his cycle at Barcelona has come to an end and that's what he expressed to Barça in writing, via burofax, on Tuesday. The club responded to Messi immediately to let him know the clause wasn't active right now and, as such, he would form part of the squad next season. On Sunday the first-team squad will all undergo PCR tests ahead of preseason training beginning on Monday.
Shortly afterwards, reports in Argentina claimed Messi wouldn't go on strike. Leo is aware that if he wants to move he can't go to war with the club. This is why Messi is expected to arrive in Barcelona on Sunday to take the COVID-19 tests and later begin preseason training if no agreement has been reached. Barça have made it clear they won't negotiate their captain's exit and now doubt he'll appear on Sunday.
In the burofax that Messi said it claims he is activating his clause "effective from the 30th August". Barça believe that if Messi appears on the 30th for tests or the 31st he would be going against the information contained in that burofax.
Whilst Messi's lawyers may see that as an interpretation of the initial message, there's nothing stopping Leo from sending another burofax to clarify his stance on a possible transfer away.