I think Alonso is being very smart here. Taking over from a manager of long tenure and success is invariably a fraught succession see United and Arsenal for examples. Alonso is also very early into his managerial career. I haven't a notion as to who should succeed Klopp. I don't want Mourinho and would be amazed if he was considered. Ange is showing potential but we need a proven winner at the highest level. Klopp had great pedigree when we hired him. I don't envy the owners in picking Klopp's successor.
Arsenal and United were very different situations. Both were run in a more old school way, with the manager controlling everything for many years. Wenger/Ferguson both left gaping holes in their clubs when they left, and both clubs responded by trying to hire a manager to fill that gap instead of setting up a structure to aid the new manager in advance. Both also left not particularly great squads behind; Arsenal were a mess and United won the title but were pretty old and largely won it due to a lack of competition and opponents often conceding defeat before kick off.
Klopp has had more control in recent seasons but the recruitment team never left, and now we have both Edwards and Hughes in place to ensure standards remain high and the manager just needs to focus on coaching. We also probably have the strongest squad we've ever had under Klopp, largely full of young players.
It's funny, people keep repeating this line that following a manager like Klopp is incredibly difficult, but if this is such a commonly held opinion then surely that means that expectations will be lower as a result, thus actually making Klopp relatively easy to follow on from?