There goes our days of owning the 76ers.
The Sixers are all-in on the next few years.  The Celts don't need to worry about the next few years.  The focus for the Celtics is being ready to compete a few years from now.
Yes, they just signed Kemba, but he's a stop-gap.  The Celts will still be a playoff team and will win a playoff series or two.
The Celts can't really hope to match up with the Sixers now barring injuries or a major leap from Tatum.  That's OK ... the Celts time is later.